86 BULLETIN 2 01, UNITED STATE'S NATIONAL MUSEUM 



tive nature of the genus in having biramous pleopods, in the female. 

 It is clear, also, that the genus apart from the female pleopods is 

 essentially a Gastrosaccus. 



This species was originally described from specimens taken from 

 a gadoid fish. In this collection there are two specimens from the 

 same locality as the type, collected by the same collector, also from 

 the stomach of a gadoid fish. It is possible that they are really 

 cotypes from Czerniavsky's original material. The record above of 

 this species from the stomach of Oidemia deglandii probably means 

 that the bird had acquired them from fish on which it had been 

 feeding. 



ARCHAEOMYSIS MACULATA (Holmes) 



Figures 23, 24 



Callomysis maculata Holmes, 1894, p. 582, pi. 20, figs. 36-44 ; 1900, p. 224. 

 Archaeomysis maculata Tattersall, 1932a, p. 304, figs. 1-13. 



Description. — In order to make this account of the American 

 Mysidacea complete I reproduce the description and figures that I 

 published in 1932: 



Length. — Adult female, 12 mm. 



Description. — Carapace (fig. 23, a) produced in front into a mod- 

 erately long, acutely pointed rostral projection, extending anteriorly 

 to the distal margin of the eyes ; posterior dorsal margin of the cara- 

 pace without a fringe of lappets but with two simple digitate lobes, 

 not forwardly directed. 



Fifth abdominal somite with the median dorsal posterior margin 

 drawn out into a laterally compressed acute spine overlapping the 

 sixth somite for about one-quarter of its length. Sixth abdominal 

 somite one and a half times as long as the fifth. 



Antennular peduncle (fig. 23, a) with two spines on the outer margin 

 of the second joint. Antennal peduncle (figs. 23, a, 24, a) as long 

 as the first two joints of the antennular peduncle; distal joint quite 

 short. Antennal scale (figs. 23, a, 24, a) shorter than its peduncle, 

 slightly longer than the first joint of the antennular peduncle, four 

 times as long as broad, with a distinct distal joint marked off by an 

 articulation; outer margin entire and terminating in a very pro- 

 nounced spine projecting well beyond the apex of the scale. Lab- 

 rum produced into a well-marked forwardly projecting spine. 



Carpopropodus of the endopod (fig. 23, d) of the third to the 

 eighth thoracic limbs divided into from 8 (in the third) to 12 (in 

 the eighth) sub joints; expanded basal plate of the exopods of the 

 thoracic limbs with 2 small spines on the outer distal corner in the 

 second to the seventh pairs, rounded in the first and last. 



