CAPRELLIDAE OF WESTERN NORTH ATLANTIC 111 



Stebbing (1906) defines the Caprellidae as Amphipoda which have the: 



Head fused with 1st segment of peraeou. Palp of maxillipcd 1- to 4-jointed. 

 Peraeon often with fewer than 7 pairs of legs; 2, rarely 3, segments of peraeon 

 with branchial vesicles; 2 segments in female v.'ith marsupial plates; 1st joint of 

 gnathopods and pcraeopods wanting. Pleon and its legs rudimentary. Eyes small, 

 1 pair. Hepato-pancreatic tubes 2, rectal glands none. Heart with 3 pairs of ostia. 

 Posterior ganglia of ncrve-ch;iin very small, none situated in pleon. 



The following facts should be considered before placing this im- 

 portant linlv in the Gammaridea: 



1. No gamniaridean bears rudimentary appendages on pereonites 

 3 and 4 ; however, in Neoxenodice they are reduced though normally 

 segmented. Cajrrogammarus (fig. 49c) bears 2 [? l]-segmented ap- 

 pendages on the pereonites and the reduction of these appendages is 

 in the Caprellidea. 



2. Gammarideans have at least 4 pairs of gills with the exception 

 of Neoxenodice which has 3 pairs. Cap'ogaminarus bears only 2 pairs 

 as is common in the Caprellidea. 



3. Gammarideans have at least 4 pairs of incubatorv'- plates, al- 

 though the number is not knov/n for Neoxenodice. Caprogammarus 

 bears only 2 pairs as is common in the Caprellidea, 



4. Most caprellids do bear small coxal plates on pereonites 1 and 2 

 and 5-7 which, as in Cercops and Aeginella, are as well if not better 

 developed than in Caprogammarus (fig. 3f), 



5. Some rather advanced caprellid genera such as Aeginella and 

 Proaeginina have only a partial fusion of the cephalon with perconite 1 

 and the suture between them is quite distinct. 



6. The abdomen of Cercops consists of 5 somites and bearing in the 

 male what could be considered 2 pairs of very rudimentary^ pleopods 

 and 2 pairs of uropods. 



7. Maxilla 1 of gammarideans always bears an inner lobe (fig. 49b) 

 which is absent in the Caprellidea (fig. 49f). Caprogammarus was de- 

 scribed as bearing an inner lobe (fig, 49d). The only irreconciliable 

 differences between the Caprogammaridae and the Caprellidea are 

 the presence of a telson, biramous pleopods, and an inner lobe on 

 maxilla 1 in Caprogammarus. The telson of Caprogammarus is very 

 small and may represent the doi-sal anal lobe which is sometimes 

 quite large in the Caprellidea. The inner lobe in the figures of maxilla 1 

 of Caprogammarus seems to be of quite unusual shape and is even 

 larger than that of Neoxenodice. It miglit be that the figures are not 

 of an actual lobe but of some distortion caused during dissection. 

 Regrettably, I have not been able to obtain specimens of Caprogam- 

 marus so I must rely on Kudrjaschov and Vassilenko's description 

 and figures. The biramous pleopods and the inner lobe of maxilla 1 



