CERATOMYSIS. 227 
CERATOMYSIS Fax. 
Bull. Mus. Comp. Zool., XXIV. 220, 1893. 
Integument soft and membranaceous. Cephalo-thorax robust. Carapace 
short (leaving the last two segments of the thorax exposed), spinose ; frontal 
margin truncate, armed at the external angles with a pair of long horn-like 
Spines ; a conspicuous rounded notch near the anterior end of the lateral 
margins, serving as an excurrent orifice from the branchial chamber. Abdo- 
men cylindrical, spinose, sixth segment not much longer than the fifth; 
telson very long and narrow, truncate at the distal end, setose on both mar- 
gins. Eyes absent, their stalks assuming the form of slender styles whose 
tips are soft and delicate, perhaps serving as tactile organs. Peduncle of the 
first antennx rather short, reaching only to the proximal end of the last seg- 
ment of the peduncle of the second antenne ; flagella much longer than the 
peduncle, flattened and fringed with long sete on their margins. Peduncle 
of second antenne long and slender, distal segment the longest ; scale long 
and very narrow, ciliate on both the internal and external borders. Mandib- 
ular palps long, reaching some distance beyond the distal end of the pedun- 
cle of the first antennz ; second segment longest, third segment long oval, 
its margins ciliate. Maxillipeds devoid of exopods, but furnished with an 
internal porrect lobe ; the fifth and sixth segments are somewhat pyriform, 
with their inner margins protuberant and furnished with sete; the seventh 
or terminal segment is small and is armed with two or three stout spine-like 
sete. The first pair of legs or gnathopods, like the following pairs, is fur- 
nished with long exopods; the fourth segment, moreover, is produced on 
the inner side to form a very long porrect lamina; the distal segment of 
these appendages is oval, and ciliated on the margin. The following pairs 
of legs are long and slender, the propodites of the last three pairs indistinctly 
segmented ; the dactyli of the second, third, and fourth pairs are short and 
unguiform, those of the fifth, sixth, and seventh pairs long and lanceolate. 
The first to the fifth abdominal segments bear each a pair of appendages 
which increase in size from before backward; these appendages are all 
simple save the left one of the fifth pair which carries (in the unique type 
specimen) a slender lateral branch (Plate LVI., Fig. 1°). Both branches of 
the uropods are linear, setose on both margins, subequal in length, shorter 
than the telson; the outer branch is not divided by a transverse suture. 
Seven pairs of incubatory lamellz in the female. 
