1382 



CRUSTACEA. 



Figures 7 a, a', b, c, represent a young individual probably of the 

 Corycceus deplumatus. It was obtained October 13, 1838, along with 

 that species. Fig. 7 a' is a side view of the abdomen and posterior 

 part of thorax ; b, the antenna ; c, the organs of the following pair. 



Figure 8 may possibly be young of a Schizopod. It was obtained 

 at the east entrance of the Straits of Sunda, March 5, 1842. 



In all the young animals of the Cyclops and Caligus groups of 

 species, there are six pairs of appendages in their earliest state, and 

 the anterior of these pairs, in the species examined by the author, is a 

 pair of antennae, corresponding evidently to the posterior antennae of 

 adults. We draw attention to this fact, from its bearing upon the 

 homologies of the young in other groups. 



II. ARACHNOPODA or PYCNOGONOIDEA. 



The Arachnoid Entomostraca have been made a special study by 

 Johnston,* Kroyer,f and Quatrefages ;{ Johnston drew out the first 

 lucid description and arrangement of the genera; Kroyer gave more 

 definiteness to our knowledge of the external structure of these 

 animals, and corrected some erroneous notions with regard to the 

 relations of the parts; and Quatrefages has developed with much 

 beauty their internal anatomy. Other authors have contributed to 

 this branch of science, among whom Edwards,§ Erichson,|| and Good- 

 sir,^ are the more prominent. 



* a. Johnston, M.D., Miscellanea Zoologica, Mag. of Zool. and Botany, i. 368. 

 | Nat. Tidsskr., iii. 299, and [2], i. 95, and Oken's Isis, 1841, 714, 1846, 429. 

 % Ann. des Sci. Nat. [3], 1844, iy. 69. 



§ Crust., iii. 530. II Entomographie. 



Tf Jameson's New Edinb. Phil. Jour., xxxii. 136, 1842, xxxiii. 367; Ann. Mag. Si. 

 Hist., xv. 293, 1845. 



