Monograph of the Genus Callinectes. 567 



tube is the narrow muscle which Keferstein describes, 

 along which the saccules are attached] : (" four cylindric 

 or flat bundles of muscular fibres, free in the gelatinous 

 mass,") [according to Keferstein's figure the muscular 

 cords are situated half-way between the centre and surface 

 of the pedicel] : (" the radial muscles of the swimming sac " 

 [oral side of the disc] " occupy the middle line of each arm,") 

 [running from the proximal end of the partitions; as in H. 

 auricula, this is, doubtless, merely a more strongly devel- 

 oped margin of the principal muscles which occupy the 

 whole area about the partitions, between the genitals] ; 

 (" gelatinous mass " [gelatiniform layer of the aboral side] 

 " a massive layer ; it fails in the swimming sac," [oral 

 side] ; " in the stem solid between the four tubes,") [as in 

 the two foregoing species] : (" on the surface of the swim- 

 ming sac [the oral side] heaps of nettling capsules lie 

 in little pockets").* Geographical distribution : Norway, 

 Sars ; St. Vaast la Hogue, north coast of France, Kefer- 

 stein.f 



Art. XIII. — Monograph of the Genus Callinectes. — By 



Albert Ordway. 



[Communicated Jan. 7th, 1863.] 



[The following paper consists of selections from notes 

 made by Lieut. Ordway during his study of the Portu- 

 nidce with the view of monographing that group of Crus- 



* While the above was in press, I received specimens of this species from Kefer- 

 stein, and am able, therefore, to confirm what I have quoted from this author. 



t I would bo glad to receive from the Kuropeau coast specimens of any of the 

 Lucernarians, and most especially of the following: Craterolophus Thetys, C. con- 

 volvulus, Depastrum cyathiforme, Iluliclystus octoradiata, for which I will send in 

 exchange abundant specimens of our common Haliclystus auricula. I will state 

 that I have already sent specimens to Europe by mail, in little bottles about an inch 

 and a quarter long, inclosed between two pieces of cork hollowed out. Ucnry 

 James- Clark, Harvard University, Cambridge, 3Iassachuseiis. 



APRIL, 1863. 



