182 Mr Henry Goodsir on a new Genus ^ 



antennae arise immediately behind the base of this spine, they 

 are biarticulate, with the peduncle large. The palpi arise 

 immediately behind, and the branchia are in visible and con- 

 stant motion below the carapace at this spot. The legs are 

 four in number, the first pair at this time composed of two 

 parts, an external and an internal. The external, like those 

 of the Cancer Pagurus, are plumose, being armed at the ex- 

 tremities with three or four strong plumose spines ; the in- 

 ternal part arises from the extremity of the first joint ; it is 

 multiarticulate, and armed at the extremity with a claw ; 

 there is no appearance of this division on the last pair of legs. 

 The abdomen is five-jointed, the last joint armed with two 

 long and curved spines, bearing a number of smaller spines on 

 their inner edge near the base. The intestinal canal is ob- 

 served running along the lower edge of the abdomen, and the 

 heart may be observed at the base of the dorsal spine, beat- 

 ing synchronously with the motions of the branchia. If the 

 young animal is freed from the tunics of the ovum a few days 

 before hatching, its appearance is perfectly different (fig. 16, 

 PI. III.) The antennae are long and slender. The eyes are 

 small and sessile, and the caudal fork is armed with a num- 

 ber of curious brush-shaped appendages. (Fig. 17. PI. III). 



The Zoe of the Pagurus (fig. 12. PI. III.) when it escapes 

 from the egg, or a short time after, is perfectly transparent, 

 the thoracic portion of the body is slightly opaque, and the 

 eyes are black. The abdomen, however, is perfectly translu- 

 cent, and the observer requires to look very attentively before 

 it can be defined. On being excluded from the egg, the 

 young animal is doubled upon itself ; the abdominal portion 

 of the body is bent closely under the thoracic portion, and it 

 is kept in this position by means of a very thin sae or mem- 

 brane. 



It very soon frees itself from this by a few violent effbrts, 

 and then the antennae, the feet, and the abdomen, all become 

 free and extended. The proximate half of the abdomen only 

 is confined within the sac, the distal half is quite free. The 

 Zoe of this species is destitute of spines, the spine on the dor- 

 sum of the carapace and the frontal spine being absent. 

 As soon as the young animal frees itself of the sac beford 



