504 



I'ROCKEDINaS OF THE NATIONAL MUSEUM. 



VOL. XXVIII. 



fiCi. 11.— FlKST MAXILLIl'ED i 

 LEPEOI'IITHEIRUS edwakiisi 



the first. K;icli is made up of two joints, the basal of which is inucli 

 swollen and liberally su])plied with stout nuiseles, while the apical 

 one is a powerful claw curved over inward and carrying a spino 

 on its inner margin (lig. I'J). 



These are the chief organs of prehension, 

 as already noted, and are usuall}" much largei- 

 ill the male. Their relative size, however, 

 varies greatly in the difl'erent species and 

 gcniera; in one they are evidently the chief 

 reliance for clinging to the host or to the 

 female; in another the second antenna^ are so 

 much enlarged and the tirst maxilhe in the 

 male are so stout that these maxillipeds evi- 

 dently share the honors at the least. 



Lcpcophtlu'n'u^i innomtnatiis is a good exam- 

 ple of the former, the l)asal joints of the second 

 maxillipeds being so large as to till the cen- 

 tral portion of the carapace (Plate XXVIII). 

 And Cal!(/nx ,srh/sf<tny,r is a good example of 

 the latter, the terminal claw of the second maxillipeds being small 

 and very weak wliile the second anteniue are large and stout (Plate VI), 



In many other species the 

 two are just about equal in 

 strength and efficiency. 



Between the swollen basal 

 joints of the second maxilli- 

 peds arises the furca or sternal 

 fork, which consists of a stout 

 chitiu plate whose tip is l)iiid, 

 much like an old-fashioned 

 bootjack. 



It varies consideranly in form 

 and relative size in the ditfer- 

 ent species, and for some au- 

 thors it serves on this account 

 as a secondary l)asis of classifi- 

 cation. It is f re(piently of con- 

 siderable service in this direc- 

 tion, and in on<> or two cases 



is sufficiently diifei-ent to serve as tlu> distinguishing characteristic of 

 the species. Witness the double bifurcation in Lepcophtheinis hlj)- 

 2)()<il(»<x! and L. l!fi(rc<if}(s^ and the p(M'uliar form in the genus Gloio- 

 pofrx jind in CaHfjns plufi/fars:, and the entire al)senc'e of this append- 

 age in the genus Alchion (see Plates XX, XXIII). Several uses have 

 been suggested for the appendage. 1. C. Thompson thinks that it 



V\(i. 12.— The second maxillipeds of the adult 



('ALKiUS BONITO. UPPER FIGURE, THE MALE, W-ITll 

 A LARfiE BONY PLATE ON THE BASAL JOINT; LOWER 

 FKil'RE, THE FEMALE. 



