108 CRUSTACEA. 



means of several vesicles placed at the base of the fom- 

 jjau's of legs, commencing vvith the second or third pair, 

 including those of the head, which latter represent the four 

 anterior foot-jaws greatly developed. No other respiratory 

 organs have been observed. According to Savigny, they 

 approach the Pycnogonides, and thus lead the way from the 

 Crustacea to the Aracknida. 



The order is divisible into two families : — 



1. Cy amides {Ovalia Latreille), having the body oval, 



with transverse segments ; and, 



2. CapreUidcB {Filiformia Latreille), having the body 



long and slender, and the segments longitudinal. 



The type of the CyamidcB is a cm-ious species, parasitic on 

 the whale. 



Sometimes these creatures are so abundant upon the whales, that 

 the infested animals can be easily recognized at a very considei-able 

 distance by the white colour which they impart to the whale, and 

 which is visible when it rises to the surface. When these para- 

 sites are removed, the surface of the body is found to be deprived 

 of the epidermis, and as it w ere corroded. They are ovovi\1pa- 

 rous, producing eggs which are received into and hatched within . 

 the pouchhke plates on the under-sidcs of the centre of the body, 

 at times eggs alone, at others both eggs and young, and at others 

 young only, being observable in the pouch. Cyamus ovalis and 

 gracilis are stationary, being found in great numbers agglomerated 

 upon the corneous eminences of the Balcena imjsticetus. C. erraticus 

 is, however, organized for its wandering habits, being of a slender 

 form and with stronger legs serving for prehension. The young 

 ones appear ^vitll all the characters of their kind, only the head is 

 rather large, and the supposed branchial appendages, instead of 

 being long and slender, are short and somewhat globose; the females 

 of C. ovalis cover their young with their bodies, wliilst those of 

 C. erraticus abandon their young, conformably to their own mode 

 of hfe ; and in C. gracilis the females, males, and young, are all 

 found mingled together. (See the memoir by Roussel de Vau- 

 zeme, in the Annales des Sciences Nat., May, 1834.) 



The curious insects composing the family Caprellidee are 

 of comparatively small size, seldom exceeding an inch in 

 length. They are generally found amongst marine plants. 



