618 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
molitor , and compared them with those occurring elsewhere. Regenera- 
tive colls, from which the new epithelium is derived, appear as sub- 
epithelial islands in very young larvae, but it is only when the meta- 
morphosis begins that they give rise to the elements which form the 
imaginal epithelium. As in Muscidae the disruptions begin with an 
energetic contraction of the muscular layer, and the old mid-gut 
epithelium is raised off. Its disintegrating cells are held together in 
a “ cyst ” by their membrana propria, and form “ the yellow body.” 
The muscles undergo gradual disruption without active invasion by 
phagocytes as occurs in Muscidae. Korotneff compared the two modes 
to chronic and acute pathological processes. As soon as the larval 
muscular layer has been disrupted, nuclei arc seen surrounding the 
epithelial cylinder. Whether these nuclei are old or new elements is 
doubtful, but the small cells of which they form the centres become the 
fibrils. Rengel’s opinion is that many muscle-cells survive the general 
revolution, just as a large number of epithelial-regeneration-cells persist. 
The latter give origin to the epithelial cylinder, the former to the 
muscular layer. 
Digger-Wasps.* — Dr. A. Handlirsch supplies an appendix to the 
monograph which he published eight years ago on the digger-wasps 
related to Nysson and Bembex. The appendix includes descriptions of 
many new forms and a general discussion of the geographical distribu- 
tion of digger-wasps. The author finds it most convenient to recognise 
three main regions: — (1) the Old World, with pakearctic, Ethiopian, 
and Indo-Malayan divisions ; (2) the New World, with neotropical and 
nearctic divisions ; and (3) the Australian regions. Apart from ento- 
mology the general discussion of distribution is of importance. 
Diptera of St. Vincent, West Indies.t — Prof. S. W. Williston, as- 
sisted by Prof. J. M. Aldritch, has drawn up a report on the Diptera of 
St. Vincent, collected by Mr. H. II. Smith, who was sent to that island 
to assist the committee appointed for investigating the flora and fauna 
of the West Indies. The collection described in the present memoir is 
the first of any extent that has been studied from the West Indian 
Islands. Scattered species, or small collections, chiefly of the larger 
forms, have been studied by various authors, but no collection has ever 
represented nearly so fully as this the smaller flies. The West Indian 
Dipterous fauna is essentially a common one, with a strong South 
American facies. Very few of the species will, it is believed, be found 
restricted to any single island or group of islands. Few, however, will 
be found to occur in North America, and they, for the most part, are 
either widespread 'species, or else confined to the southernmost portions 
of the United States. With a naivete which is somewhat amusing in 
an entomologist, Prof. Williston remarks that “ it may perhaps occasion 
some surprise that so large a portion of the foregoing species are deter- 
mined as new.” The fact is due to the small size of most of the species 
in the collection, and the difficulty of distinguishing small obscure 
species from South American forms already described. 
* SB. Ak. Wiss. Wien, civ. (1895) pp. 801-1079 (2 pis.). 
f Trans. Entomol. Soc. Lond., 1896, pp. 253-446 (7 pis.). 
