ZOOLOGY. 001 



the other M. cirriferum. The relations of this type to other animals 

 have been involved in donbt, and various discrepant opinions have been 

 entertained respecting its proper systematic position. 



TheMyzostomids are minute disk like animals, sometimes almost per- 

 fectly round and with markings recalling the marks on the face of a 

 watch. They are i)arasitic on Crinoids. The question of their relation- 

 ships has recently been discussed by ])r. L. von Graff and Dr. J. Beard. 



Dr. von Graff thinks that they are related to the Tardigrades, and in- 

 deed proposes to take that group, as well as the Linguatuloids, from the 

 Arachnids and combine them with the Myzostoniids in a special class, 

 which he names Stelecho])oda. 



Dr. Beard had the opportunity to study the embryology of the type 

 and has been led to consider them as cha}to[)od worms which have he- 

 come degenerate through i)arasitism. 



The collections of the Challenger expedition of Crinoids were examined 

 for these parasites, and a large number of new species were thus ob- 

 tained. Of sixty-eight species detected on the Challenger Crinoids, fifty- 

 two were new, and one of these was the type of a very peculiar family 

 named Stelechopodidas. {Rep. Voyacje Challenger^ Zool, v. 10; Kature, 

 V. 31, pp. 165, IGG; Mitth. Zool. Stat Neapel, V. 5, pp. 5M-5S0, 2 pi.; 

 J. R. M. 8. (2), V. 5, pp. 66-09.) 



ARTHROPODS. 



Crustaceans. 



The .stomach of stalk- eyed Crustaceans. — The stomach of the podoph- 

 thalmous or stalk-eyed Crustaceans and its api)roaches exhibit some 

 interesting features, and especially in the armature by the stone-like 

 grinding pieces. The entire subject has been made the theme of 

 study by M. F. Mocquard,*and his investigations have not been limited 

 to the stomachal armature, but have extended likewise to the nmscles 

 as well as the nerves. In every natural family, according to j\[. Moc- 

 quard, the stomachal apparatus is, as a rule, disposed on some special 

 plan which is typical for each of them. There is, in the first place, 

 a distinction which is quite trenchant between the brachyurous and 

 macrurous Crustaceans. In the former, there is a narrow triangular 

 mesocardiac piece, and elongated horizontal pterocardiac ones, but in 

 the latter, the mesocardiac piece is very wide and the pterocardiac ones 

 short and almost vertical. The anomurans show, in this apparatus, 

 the heterogeneous character of the gioup, <br some are like the macru- 

 rans and others like the brachyurans. In the brachyurans, the gastric 

 skeleton, with but few exceptions, is quite uniform, but in the macrurans 

 there is great diversity. The various modifications are of systematic 

 importance, and in many cases may give essential help in determining 

 the relations of the various forms. As an instance, oncof the results 

 reached by M. Mocquard may be noticed. Ocypiididuj are divided into 



