THE STOMATOPODA. 319 



is particularly well seen to be the case in Squilla scabricauda 

 (Fi<r. 83), where five completely developed posterior thoracic 

 terga can be counted, uncovered by the short carapace, be- 

 neath which the terga of the three anterior thoracic somites 

 are represented by a membrane which passes forward to be 

 reflected into the carapace. 



The free somites of the thorax, and those of the abdomen, 

 in this species and in the Stomatopoda generally, are so large 

 relatively to the carapace, that the latter is not larger in pro- 

 portion to the body than the tergal covering of the head in 

 many Edriophthalmia, with which order the Stomatopoda 

 present many marked affinities. Indeed, if we leave the eyes 

 out of consideration, the organization of the Stomatopoda is 

 more Edriophthalmian (and especially Amphipodan) than 

 Podophthalmian. The five anterior pairs of thoracic members 

 are turned forward, and are subchelate. The first pair are 

 ^srnall and slender. The second pair are the largest of all, 

 and have the characters of powerful prehensile limbs, the ter- 

 minal curved and spinose joint of which shuts down into a 

 groove in the penultimate joint, as the blade of a pocket-knife 

 does into its handle. The three posterior thoracic limbs, on 

 the other hand, are turned outward, and terminated by an 

 endopodite and an exopodite. 



Squilla lays its eggs in burrows in the bottom of the sea, 

 which the animals inhabit. The earliest condition of the free 

 larva is not fully known, but the young larvae have a single 

 eye, and the hinder thoracic and the abdominal appendages 

 are not developed. 1 The larvae pass into forms which, under 

 the names of Alima, Erichthys, and Squillerichthys, were 

 formerly considered to be independent genera. Claus's inves- 

 tigations, however, have rendered it probable that the two 

 latter genera are simply larval stages of Gonodactylus, and 

 that Alima is a larval stage of Squilla. 



Fritz Miiller, u Fur Darwin." See also Claus, " Die Metamorphose der 

 Squilliden," 1872. 



