278 METAMORPHOSIS 



in the present Memoir, to adduce proofs of the same thing in 

 another genus, viz. that of Portunus. 



The genus Carcinus appears to connect the genuine crabs 

 (Arcifati,) with those of the natatory division to which Portu- 

 nus belongs ; which therefore offers, very apropos, the second 

 illustration of this curious fact. The most striking character 

 of this genus, is to have the hinder, or fifth pair of members, 

 formed like paddles, for swimming; and which, when the 

 animal crawls, are bent up over the other feet. 



Several species of Portunus inhabit the harbour of Cove, as 

 depurator, arcuatus, corrugatus, and marmoratus, of which 

 the last is perhaps the most common. One of this species 

 (P. marmoratus) being dredged up with spawn ready to hatch, 

 has enabled me to observe and sketch its Zoe, (tig. ^,) which 



Fig. 2. 



bears a considerable general resemblance to those previously 

 depicted of Cancer pagurus, (Zool. Res. PI. VIII. fig. 1,) 

 and of Carcinus mcenas. In all these instances, it may be 

 observed, that I had myriads of the fully-developed larvae 

 before me, and not solitary specimens ; some struggling to 

 extricate themselves from the envelopes of the ova, others 

 swimming about in full activity. So great indeed is the 

 resemblance of the Zdm of the above-named genera, that did 

 we not know others of a different form, as Leach's Zde, clavata, 

 the Zo'e of Pinnotheres (see p. 90), and that of Porcellana 

 of the preceding Memoir, we might be apt to suppose a 

 general correspondence in this respect in the larvae of all the 

 Brachyura. 



As it will hardly ever be possible, by any contrivance, to 



