102 PROGRESS OF MICROSCOPICAL SCIENCE. 



to all the Natural History world. It is of such great length and so 

 numerously annotated, that we cannot do more here than recommend 

 it to the attention of our readers. 



Scales of Butterflies and Gnats. — There would appear to be a sin- 

 gular resemblance between the scales of these two insect groups. In 

 the above-mentioned paper the author says: — A fact casually dis- 

 covered by me, and of which I find no mention hitherto, seems to me 

 of great importance in the systematic disposition of this order. In 

 the spring of 1868, while engaged in examining the head of a gnat, 

 with a view to ascertain whether or not the valves of its proboscis had 

 the transverse bands of chitine, I was surprised to discover that the 

 proboscis and palpi were clothed with scales entirely like those of but- 

 terflies. I find no mention of this important fact in the special works 

 of Meigen and Schiner which are in my possession. Meigen simply 

 points out that in Culex, Anopheles, and Corethra, scaly productions 

 are observed on the venation of the wings, and he figures some of them, 

 which, however, being quite narrow and with two sharp points, have 

 no analogy with real lepidopterous scales. The gnat-scales observed 

 by me closely resemble the most characteristic lepidopterous scales. 

 They suddenly dilate from a short and narrow peduncle to a large 

 scutiform surface which is traversed longitudinally by a few parallel 

 ridges, between which, when more highly magnified, transverse wavy 

 lines, very fine and numerous, are seen. The only difference which 

 these scales present compared with those of butterflies is, that in the 

 former the transverse lines are not so fine, so regular, nor so regularly 

 distributed over the whole surface ; also these lines are entirely want- 

 ing upon the scales of some species of TipularisB. Finally, while the 

 real lepidopterous scales are always deeply crenate at their truncated 

 extremity, the scales of gnats are not ; and their truncated extremity 

 terminates in a very fine margin, from which the points of the longi- 

 tudinal ribs sometimes project. 



The Position of the Brachiopoda. — At a recent meeting of the 

 Boston Society of Natural History, Professor Hyatt said his objections 

 to Professor Morse's classification of Brachiopoda had heretofore rested 

 wholly on the presumed affinities of the Polyzoa and Ascidia. He had 

 been led by the similarities of the adult animals of the two groups to 

 partially follow Professor Allman in his opinion that these two groups 

 were closely related. In a paper " On the Fresh-water Polyzoa"* he 

 had compared them, but had at the same time shown that the difierences 

 were much greater between the Polyzoa and Ascidia than between the 

 former and the Brachiopods. Thus, there is no muscular system in 

 the Ascidia which can compare in any sense with that of the Polyzoa ; 

 and in transforming the Polyzoon into an Ascidian, Professor Allman 

 is obliged to violate this obvious difference, as well as to efffect many 

 changes which are not consistent with their organization. The nearer 

 affinity of the Polyzoa and Brachiopoda is hardly questionable since 

 the investigations of Koraleusky, who has shown us that the young 

 Ascidians are apparently more like young vertebrata than they are 

 like the young of the Polyzoa. The importance and value of the 

 * ' Proceedings [American] Essex Institute,' vol. iv. 



