108 CRUSTACEA. 



means of several vesicles placed at the base of the tour 

 pairs of legs, commencing with 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 Pycnoyonides, and thus lead the way from the 

 Crustacea to the Arachnida. 

 The order is divisible into two families : 



1. CyamidoK (Ovalia Latreille), having the body oval, 



with transverse segments ; and, 



2. Caprellidee (Filiformia Latreille), having the body 



long and slender, and the segments longitudinal. 



The type of the Cyamidae is a curious 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 considerable 

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

 which is visible when it rises to the surface. \\ lien tlioc para- 

 sites are removed, the surface of the body is found to be depri\ed 

 of the epidermis, and as it were corroded. They are ovovhipa- 

 rous, producing eggs which arc received into and batched within 

 the pouchlike plates on the under-sides 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. Cyamw ovalis and 

 gracilia are stationary, being found in great numbers agglomerated 

 upon the corneous eminences of the BaUena mysticetu*. 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 with all the characters of their kind, only the bead 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, whilst those of 

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

 of life ; and in C. yracilis the females, males, and young, are all 

 found mingled together. (See the memoir by Roussei tie Vau- 

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



The curious insects composing the family Ciijtrrlliiirr are 

 of comparatively small size, seldom exceeding an inch in 

 length. They are generally found amongst marine plants. 



