12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 59 



organs. In Oxystomina (fig. 8) the amphid is very remote from 

 the anterior end and becomes very much elongated, with a large 

 anterior aperture, the reverse of the common condition. The 

 cephalic circle of the setae is divided into two circles, with six setae 

 in the anterior and four in the posterior circle, an evidence of its 

 complex nature. Halalaimiis (fig. 9) presents a further step in the 

 elongation of the amphids, so that the primitive pocket form could 

 hardly be recognized without the intermediate Oxystomina. 



The Phanodermatinae in its most simple members, for example, 

 Crenopharynx, closely resembles the Leptosomatinae as regards the 

 structure of the head. The differences are in the always elongated 

 spicules and the esophagus of a distinct cellular structure. The 

 type genus PJmnoderma (fig. 10) is ocellate and has a cephalic 

 capsule like Thoracostoma but of a different type, four-lobed in- 

 stead of six-lobed, and followed by a cephalic armor probably 

 homologous to that of the Enoplinae. Several other genera closely 

 resemble Phanoderma. 



The Thoracostomopsinae are very distinctive. The cellular 

 esophagus and the four-lobed cephalic capsule resemble those of 

 Phanoderma, but there is a peculiar spear followed by a modified 

 part of the esophageal tube, to which the spear is joined by an 

 articulation. 



The Oncholaiminae have a spacious mouth capsule, provided in 

 typical representatives with three immobile onchi (fig. 11). Gen- 

 erally they do not have the preanal organ typical for all the three 

 preceding subfamilies, although Pontonema has a reduced one, so its 

 absence in other genera could be considered as secondary. The 

 existence of the spacious mouth capsule does not permit the 

 esophageal musculature to adhere to the cuticle directly as in the 

 previous forms. But there is the same duplication of the cuticle on 

 the head as in Leptosomatum, and the cuticle of the mouth capsule 

 is folded in that place. Actually the mouth capsule is nothing other 

 than the enlargement of the interior of the esophageal tube lacking 

 the surrounding musculature; the epidermal cells that form the 

 esophagus in that region adhere over a wide area to the cuticle just 

 as do the muscle cells in other forms. Krampia should be considered 

 as a reduced Oncholainms, a parallel to the conditions in Catalaimus 

 discussed below. 



In the Rhabdodemaniinae, Rhabdodemania (fig. 12) is a very 

 distinctive genus, the only genus at present in an isolated subfamily 

 erected for it. The large buccal capsule resembles that in the 



