Decapod Crustacea of Bermuda, Part II. .?9 



That of the female, called the thclycum, serves as a spermatheca. 

 That of the male, called the pctasina, is supposed to aid in the 

 transfer of the spermatophores. The eggs are not carried attached 

 to the pleopods, as in most macrura, but are held by the legs in a 

 cluster under the body. 



Family PEN.ffiID.ffi Dana, 1852. Pra-tcns. 



I'.txlv is usually compressed and curved. The carapace extends 

 further back on the sides than dorsally ; usually it is carinated 

 dorsally ; a carina is usually present also on some of the posterior 

 abdominal segments ; the carina is often dentate. The legs of the 

 third pair are the longest ; the chelae of first three pairs are small, 

 all similar in form and size. 



Antennze are long, with a large basal scale. Antennules are 

 biflagellate. with an external basal spine and an inner unjointed 

 appendage, excavate on the upper side. The eye-stalks are usually 

 two- jointed. The lateral lobes of the first abdominal segment are 

 broad and project forward, overlapping the margin of the cara- 

 pace, while posteriorly they overlap the margin of the second 

 abdominal segment. 



In most of the genera the female has, on the under side of the 

 sternum, a peculiar sexual organ, called the "thelycum," serving 

 as a spermatheca. The male usually has, in the same region, an 

 organ called the pctasina. 



The gills are dendrobranchiate, consisting of a central stem, 

 sending off on each side a row of branches, which divide and sub- 

 divide in various ways, according to the genus, thus forming a 

 dense plume of slender filaments. There are eight or more pairs 

 of gills. 



Analytical Key to Bermuda Genera of Penaida. 



A. Dorsal carina not crest-like and dentate ; subocular, median, anterior 

 spines lacking; Pleopods biramous. Sexual orifices coxal in both 



sexes Subfamily Penteina 



B Rostrum with teeth above and below ; exopodites on all the thoracic 

 legs, except sometimes the last; epipodites on all except the fourth 

 and'fifth; pleurobranchiae at the last pair of legs; endognath of 1 



maxilla long and segmented Pcnaus. 



BB. Rostrum without teeth below ; no epipodite on the outer maxillipeds ; 



endognath of first maxillae shorter, not segmented. 



C.No pleurobranchia at the base of the fifth legs ; no epipodites on the 

 fourth and fifth legs. 



