The distribution and anatomy of sirenian perioral bristles (modified vibrissae) and facial hairs are of interest because of their use during feeding and tactile exploration. In the present study we have identified six fields of perioral bristles on the face of the Florida manatee (T. manatus latirostris), four (U1‐U4) on each side of the upper lips and oral cavity, and two (L1‐L2) on each side of the lower lip pad, inside the oral cavity and rostral to the horny mandibular pad. Each field has a characteristic location, number of bristles, and range of bristle length and diameter. There is a mean of 110 (± 19) bristles per side, with no left‐right differences. Branches of the infraorbital nerve innervate the bases of the largest bristles (U2 group) on the upper bristle pad, and the inferior alveolar nerve supplies the bristles of the lower bristle pad. The dorsal and ventral buccal branches of the facial nerve innervate the superficial facial musculature, which is likely to be involved in bristle eversion and other movements which constitute feeding behavior. Hair is denser in the facial region than on the remainder of the body. Within the face, hair is denser on the oral disk than on the supradisk. The oral disk contains bristle‐like hair, whereas the supradisk region possesses hair that is similar in length and diameter to that on the postcranial body. The mean total of bristles and hairs per face was 1,942. Means for the subregions were 220 (± 39) bristles on the perioral bristle pads, 601 (± 115) bristlelike hairs in the oral disk region, 710 (± 229) typical hairs in the supradisk region, and 411 (± 108) typical hairs on the chin. There were no significant differences between left and right side counts. Facial hair density was inversely correlated with facial area and body size. These data provide new information on the anatomical basis of the exceptional orofacial activities characteristic of manatees during feeding and tactile exploration.

Measurements have been made of the rates of oxygen consumption by the eggs of several marine forms, and especially of the change in rate following fertilization. It is convenient to present some of these results separately, considering them comparatively in one of the papers and discussing the relation to other work in the field, and some of the theoretical implications. This will be done in the fourth paper (1) of this series. The present paper will be chiefly concerned with measurements on the eggs of the clam Cumingia.In the summer of 1930 measurements of the rate of oxygen consumption of Chaetopterus eggs showed that immediately following fertilization there is a decided decrease to slightly more than half of the prefertilization rate. This surprising result was entirely unexpected, and many careful repetitions of the measurements were made, which invariably confirmed the first finding. When the eggs of Chaelopterus are taken from the parapodia of the female and are placed in sea water, dissolution of the germinal vesicle takes place and maturation proceeds until the nucleus comes to rest in the metaphase of the first polar spindle. This takes less than 15 minutes at 20°C. In this stage the egg rests until it is fertilized. When the unfertilized eggs are placed in manometers after having attained the metaphase resting condition, the rate of oxygen consumption is uniform for at least 8 hours. Fertilization at any time during this period (which was the longest experimental period) causes a sharp drop to about half.

Several species of the seaweed Fucus arr obtainable in abundance on the rocky shores of Nahant peninsula, outside the entrance to Boston Harbor. These sea \veeds have a long breeding season, shedding eggs and sperm in the winter months when other types of eggs are difficult to obtain. In 1929-30 eggs of Fucus vesiculosus were collected from October until June. Throughout this time some eggs were always obtainable from plants with relatively large fruiting tips, or receptacles, and in February. March. April, and May they were obtainable in great abundance.Fucus vcsiculosus is dioecious. The sexes can be sq^arated by sight with fair reliability if a cut receptacle is examined. The conceptacles of the male plants are orange due to the carotinoids contained in the antherozoid or sperm cells. The conceptacles of the female plants are green or brownish-L;reen, largely because of the plastids in the eggs.Identification becomes certain if a thin section of the receptacle is examined microscopically.The purpose of this paper is to present a number of observations and experiments, some of which have been incidental to measurements on respiration in the Fucus eggs which will be presented elsewhere. The results recorded here have particularly to do with the nature of the eggs and with certain factors involved in determining the first division plane. The first division of the Fucus egg ordinarily -ivrs rise to two cells of different shape. One, which includes the rhyxoidal protuberance, is the parent cell for the formation of the rhy/oid, the other gives rise by divisions to the thallus. At the first division, therefore, the polarity or developmental axis of the spore has been determined ami is first indicated. A number of environmental factors have been found capable of determining the cleavage plane and tin-polarity of the Fitcus spore. Orientation of the cleavage by a directed beam of light has been demonstrated in a number of plants (e.g., Pierce, 1906). Farmer and Williams i IS' i,X) have shown that if fertilized Fucus eggs are illuminated National Research Council Fellow in the Biological Sciences.

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