There are ar: least several thousand Icnown species of calyptrate Diptera but nre have to date cytological data on only 130 of them. T h e early report of Stevens (30), which contained soine information about the chromosomes of six species, was followed in 1916 by a report of hlletz (24), which included nliscellaneous information about th& lcaryotypes of about 16 specics. These reports and some others xvere summarized by Maleino (40). H e reported observations on four species of Anthomyiidae, five of Calliphoridae, two of Cordyluridae ( 1 Scatophagidac), one of -~,luscidae, five of Sarcophagidae, one of Tachinidae = a total of 18. During the past 18 years Ive have accumulated cytological data coilcerning 113 species belonging to various Calyptrate families. Aside from our o\\:n publications (scc references) thcrc ha\& been only occasional contributions to our lenowledgc of the Icaryology of this group up to the recent publication of the c o r~~p r e h e n s i~~e studv of Ullerich (31) concerning 11 species including five on which we had no frevious reports.T h e purpose of thc present report is to provide a summarv of presentlv ;ivailable information about the karvology of species of the calybtrate ~i~t e r a . Our initial intcntion was to cover -only chromosome nuinbers; and this could have been done by simply mentioning the species ~v i t h 271 = 12 (over 900/, of those studied cytologically), tllc few spccies n.it11 277 = 10 and thc rare cxceptions. But this would ;lot ha1.e revealed the considerable niorphological differences that exist in the autosomes of these specics nor thc very great variations that characterize their sex chronlosomes. Table I to present the more useful information extracted froin the published literature, and our o\vn unpublished materials, in :I concise form for casv referencc. T h e species are listed according to families, subfanlilies and tribes in a very simple organization, for the lnost part borrowcd from taxonomic experts such as Robaclc (43, 44), Hall (38), Hennig (39, etc.), van Enlden (35) and others. Specics are shon~n 1vit11 the naming authorities given in the original reports or as provided by those who have Itindly identified specimens for us. Synonyms have been numbered and indcnted below the genus and spccies considered to be that accepted inore recently. In several cases the different collections of ccrtain species are similarly indented and n~lmbered below the succies to which thev have been referred.. 1 i T h e nun~bers of chromosomcs seen in mitotic divisions are listed under the heading, mitotic 272 chromosomes. T h e tissues in which thcse observations An attempt is made inwere made are indicated as follows: g = larval ganglion; 8 and Q signs refer to whether the larvae were considered to be malc or female, respectively, usuallv on the basis of the ~rcsumcd sex chromoson~es: o = ovarian tissue ' . I excluding oocytes; s = testicular tissue exclucling spennatocytes; e = embryonic tissue; f = follicular epitheli~lm. Supernunlerary chromosomes (i.e. small chromosonle...

This report contains a description of the karyotypes of Musca sorbens Wied., Musca vetustissima Walker, several strains of the subspecies domestica and the subspecies curviforceps and calleva of Musca domestica L., Musca autumnalis De G., Muscina.stabulans Fall., Orthellia nudissima (Loew), Ophyra leucostoma Wied., Phaonia basalis Fabr., and Phaonia variegata Fabr. Species M. stabulans, O. nudissima, and P. variegata have 2n = 10 chromosomes and all the others 2n = 12, but some specimens of M. domestica curviforceps have only 11. The sex chromosomes of M. autumnalis and O. leucostoma are very small and this pair has apparently been lost in the 10-chromosome species. It is suggested that species having 10-chromosome karyotypes may have originated independently in different subfamilies and genera of the Muscidae.

Among plants grown from buckwheat "seeds" which had been exposed to X rays or thermal neutrons two thrum-flowered plants each had a branch bearing modified flowers. One thrum plant had a branch bearing homostyled flowers and the other a branch bearing pin flowers. A thrum plant in the progeny of the latter plant was self-fertile, produced no progeny in crosses with other thrum plants, but was fertile in crosses with pin-flowered plants. These cases are discussed in relation to a postulated S supergene controlling incompatibility in buckwheat.

The somatic chromosome complements of nine sarcophagid species are described using methods presented in the first paper of this series. These species are Acridiophaga aculeata, Kellymyia kellyi, Protodexia australis, P. hunteri, Pseudosarcophaga affinis, Sarcophaga aldrichi, S. cooleyi, Sarcophaga "H", and S. reversa. P. affinis has 19 or 20 chromosomes whereas all the others have 12-chromosome complements most of which can be distinguished.

No abstract