742 SUMMARY OF CURRENT RESEARCHES RELATINQ TO 



by a chapter on their development and immature stages, the observa- 

 tions necessary for which were the most laborious part of the author's 

 undertaking, involving the rearing of a large number of the micro- 

 scopic animals in confinement, and their careful watching and the 

 regulation of their hygrometic conditions every day for months ! 

 They had indeed to be carried about with him on any journeys. 

 Amongst the habits of the Oribatidae are enumerated their avoidance 

 of light, which increases so much the difficulties of observation, their 

 habit of carrying a portion of their cast skins and piling up dirt and 

 rubbish on their backs to form an artificial covering, or investing 

 themselves with a white substance. From the chapter which gives 

 very detailed directions on collecting and preserving, we have already 

 made some extracts.* 



The remainder of the book deals with the anatomy of the exo- 

 skeleton and internal anatomy (pp. 110-190) and with the description 

 of genera and species (pp. 191-327). 31 plates, mostly coloured (some 

 of which have appeared in this Journal in connection with Mr. 

 Michael's various papers), illustrate the text. 



A type series of slides has been deposited by Mr. Michael in the 

 Society's cabinet.f 



S. Crustacea. 



Stomach of Podophthalmate Crustacea.l — In this important con- 

 tribution to our knowledge of the anatomy of the higher Crustacea, 

 F. Mocquard, after the ordinary historical review, points out that in 

 the Decapoda there are important differential characters, distinguishing 

 the Brachyura from the Macrura, but that, as is already known, the 

 so-called Anomura belong, some to the brachyurous and some to the 

 macrurous type. When we review all the families we find in every 

 natural one that the gastric apparatus is arranged on a special and 

 characteristic type. 



In the Brachyura the mesocardiac piece is narrow and triangular, 

 while the pterocardiac ossicles are elongated and directed horizontally ; 

 in the Macrura, on the other hand, the former occupies the whole of 

 the transverse line of the superior cardiac wall, while the latter are 

 ordinarily shorter than in Brachyura and are set almost vertically. 

 Although it is true that the short-tailed forms never present the 

 characters seen in the gastric ossicles of the long-tailed, the converse 

 proposition does not hold good, for in such Macrura as have under- 

 gone some degeneration, the ossicles are formed on almost the same 

 type as in the Brachyura. The more detailed account of the differ- 

 ences between these two groups are set forth in the paper. 



In passing from the normal Brachyura to the abnormal (or apteru- 

 rous Anomura), we observe a certain number of characters inter- 

 mediate between what are seen in the Brachyura on the one hand, 

 and the Macrura on the other ; and it is to be noted that, on a con- 

 sideration of nothing but the arrangements of the parts of the gastric 

 skeleton, we should ascribe to them that intermediate position which 



* See this Journal, ante, p. 635. t Ibid., p. 500. 



X Ann. Sci. Nat. (Zool.), xvi. (1884) 311 pp. (11 pis.). 



