[71] 



DECAPODA FROM ALBATROSS UREDGINGS. 



415 



SERGESTIDiE. 



Sergesies aecticus Kroyer. 



Smith, Proc. Nat. Mus., iii, p. 445, 1S81 ; Bull. Mus. Comp. Zool., x, p. 

 96, pi. 16, fig. 4, 188-2. 



(Plate VIII, Fig. 2.) 



Specimens examined. 



III this species there is au epipocl and a well-developed podobranchia 

 at tlie ba.se of the first gnathopod, and above its base a simple lamella 

 in place of a pleurobranchia, a large anterior pleurobranchia with a sim- 

 ple lamella back of it on each of the three succeeding somites, a large an- 

 terior and a small posterior pleurobranchia on the antepenultimate som- 

 ite, and on the penultimate somite two small branchiae, of which the poste- 

 rior is very much the smaller, while the last somite is without brauchioe; 

 or, indicating the simple pleurolamell* by accents, branchial formula 

 may be indicated as follows : — 



The structure of the branchiae themselves, in this and in the two fol 

 lowing species as well, is very dilferent from that in Penceus, or any of 

 the Peuaeidse described in this paper. The branchiae are pinnate in form, 

 and each pinna is a complete phyllobranchia; that is, they are compound 

 phyllobranchicie, while those of Penceus are compound trichobranchise. 

 The structure is more like that in Slcyonia (judging by Bate's description 

 of the branchise of that genus) than that in Penanis. 



The first perajopods are subchelate, and the dactyli of the second gnath- 

 opods and the propodi of the first, second, and third perseopods are mul- 



