236 CRUSTACEANS. 



On March 4th, the parent still testified symptoms of animation, the 

 limbs partly contracted over the adhering clusters, or unfolding on the 

 under the surface. 



Thus, in conformity -with the nature of all the other Crustaceans 

 which we have hitherto discussed, the young of the Nymphon still ad- 

 heres to the parent, after exclusion from the spawn attached to its body. 



Possibly the spawn is sustained in its place by auxiliary organs. 



The animal dwells in the sea. It is not rare. 



Plate LXIV. 



Fig. 1. Nymphon gracilis, adult. 



2. Prolific female ; limbs extended, a, a, a, a ; supposed cake of spawn. 



b,l. 



3. Position assumed by the specimen, fig. 2 ; limbs, a ; supposed 



spawn, h, b. 



4. Young Nymphon hatched from the spawn, enlarged. 



5. The same, more enlarged. 



§ 8. Ptcnogonum littorale — The Whale Louse. 

 Plate LXIV. figs. 6, 7, 8, 9. 



The appearance of this animal is in strikmg contrast with that of 

 the former ; the one being light, weak, and slender, the other coarse, 

 heavy, and strong. 



It consists of a body composed of four segments, the first prolonged 

 as a rostrum, at the base of which are seated four small black eyes in 

 quadrangular arrangement. The aperture of the mouth is in the extre- 

 mity of the rostrum, for this is one of the suctorial Crustaceans ; but no 

 specimen has ever fed visibly, though offered many different substances. 

 Four pair of articulated ungulated limbs support the body, the posterior 

 extremity of which is obtuse. The claws are firmly aflSxed, to secure 

 the whole, where practicable. 



This is the most languid and inactive of all creatui'es. It is scarcely 

 ever seen to move, even to the bending of a limb ; nor does it betray 

 any propensities whatever that I have seen. 



