658 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.47. 



much narrowed posteriorly, vnih a pair of ventral posterior processes; 

 abdomen well differentiated and carrying anal laminae; egg strings 

 extending in front of the oviduct as well as behind it, and inclosed in a 

 membrane, strengthened by ribs. 



First antennae three-jointed; second antennae biramose, the 

 exopod two-jointed, the endopod simple; first maxillae bipartite, 

 without a palp; second maxillae in the form of bands, containing 

 longitudmal muscles, which clasp around the gill filaments of the 

 host; no bulla; maxillipeds of the usual pattern; a pair of spoon- 

 shaped palps attached either to the second joint of the maxillipeds, or 

 to the ventral surface of the head. 



Generic characters of male. — Cephalothorax and anterior trunk in 

 the same line and indistinguishably fused, wdthout any trace of 

 segmentation, the two covered with a dorsal carapace; posterior 

 trunk turned ventrally at right angles to the anterior portion, and 

 projecting from beneath the posterior end of the carapace as a large 

 process behind the second maxillae; anal laminae small, sometimes 

 entirely lacking. Fhst antennae three-jointed; second antennae 

 biramose, the exopod jointed and chelate, the endopod simple; fii-st 

 maxillae bipartite, \\dthout a palp; second maxillae and maxilhpeds 

 removed some distance behind the other mouth parts, about the same 

 size and armed vnih stout claws. 



Type. — NaobrancTiia cygniformis Hesse. 



(Naohranchia, ua'ao, inhabiting and ^pdyx^^^, giUs.) 



RemarJcs. — This genus is one of the most interesting in the entire 

 family. The female can be recognized at once by the flattened 

 muscle bands which serve for second maxillae, and by the fact that 

 the egg strings are carried inside of a protecting membrane. The 

 anterior part of the body of the male is similar to that of TJiysanote, 

 but the posterior body is bent sharply at a right angle and projects 

 ventrally hke an unpaired appendage behind the second maxillae. 

 These characters will distinguish either sex at a glance, and since 

 they are so totally different from all other genera it follows that an 

 account of the internal as well as the external morphology of the 

 genus ought to be interesting as well as instructive. From serial 

 sections of Naohranchia lizae we learn that the mouth tube, as in 

 most other genera, is the most anterior portion of the body. Through 

 it runs the thread-Hke esophagus {oe, fig. 121), which is bent more 

 sharply than in AchtJieres and ClaveUa, and which extends a con- 

 siderable distance behind the maxilHpeds. It enters the stomach at 

 the center of the anterior end, the entrance being surrounded by a 

 rather weak sphincter muscle. The anterior portion of the stomach 

 is) is thrown into a series of fairly regular transverse folds by alter- 

 nate constrictions and enlargements. Wlien it reaches the bases of 

 the second miixLllae these folds abruptly cease without any change 



