210 STALK-EYED CRUSTACEA. 
and unconcealed. The posterior gill of the thirteenth segment is smaller 
than the anterior gill of the same segment, being a little smaller than the 
podobranchia attached to the second maxilliped. 
This species bears a close resemblance to Sergestes mollis Smith* from the 
Atlantic coast of North America, but differs from the latter species in an 
important structural feature. In S. mollis the posterior pleurobranchia of 
the antepenultimate thoracic somite is replaced by small simple lamella, 
which is concealed beneath the following gill, while in S. inous the posterior 
pleurobranchia of the said somite is well developed and unconcealed. The 
difference between the two species is at once apparent on lifting the lateral 
flap of the carapace. 
Sergestes bisulcatus Woop-Mason. 
Plate LI. 
Sergestes bisulcatus Woop-Mason, Aun. Mag. Nat. Hist., 6th Ser., VII. 190, VIII. 353, 1891. 
Sergestes phorcus Fax., Bull. Mus. Comp. Zool., XXIV. 217, 1893. 
Carapace devoid of spines; gastro-hepatic and cervical grooves well pro- 
nounced across the dorsal part of the carapace ; a ridge runs along the upper 
border of the branchial area, giving off from its anterior end a branch which 
runs backward at a lower level along the branchial area; dorsal side of the 
carapace slightly convex in an antero-posterior sense; rostrum cristiform, 
short, laterally compressed, directed obliquely upward, subquadrate in out- 
line, the anterior margin produced to form a short point near the middle ; 
antero-lateral margin of the carapace nearly perpendicular from the base of 
the rostrum to the level of the lower side of the peduncle of the antennule, 
whence it recedes to an angle over against the base of the second antenna ; 
from this point it becomes concave, sweeping downward and backward, and 
forming ,the ciliated margin of the excurrent branchial orifice. 
The second, third, and more especially the fourth abdominal somites are 
lightly sulcate in the median dorsal line; the abdominal pleuree have rounded, 
ciliated margins ; the sixth somite is armed with a minute posterior dorsal 
spine, and is marked by a not very distinct lateral longitudinal suleus. The 
telson is suleate above, and on each side; it is shorter than the sixth abdom- 
inal segment ; distal end triangular; margins ciliated. 
The eye-stalk, with the eye, is considerably shorter than the proximal 
segment of the antennular peduncle; the eye itself is subspherical and much 
* Ann. Rep. U. S. Fish Comm. for 1882, p. 419, 1884; id. for 1885, Plate XX. Fig. 3, 34, 4, 5, 1886. 
