678 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxi. 



given the name Chelodesmidoe.^ In Ghelodesmus there is a laminate 

 process from the distal corner of the ventral side of the penultimate 

 joint of the legs, much after the manner of most Spirostreptida?, and the 

 other secondary characters are equally different from those of the Gom- 

 phodesmidaj, so that if affinity with the Chelodesmidse may hardly be 

 denied, yet the relation shii), if auy, is certainly not close, and no forDis 

 are known which could be looked upon as connecting- links. 



Family GOMPHODESMID.E Cook. 



Gomphodesmido' Cook, Ann. N. Y. Acad. Sci., 1895, IX, p. 4 ; Proc. U. S. Nat. Mus., 

 1895, XVIII, p. 82. 



Body rather small to large, robust, oblong, abruptly narrowed at 

 both ends, about five times as long as broad, the oavity somewhat 

 depressed. 



Vertex smooth, moderately and evenly convex, without hairs; sulcus 

 distinct, meeting a subtransverse interanteunal sulcus; postantennal 

 depression deep, the supj)osed sense organ large. 



Labrum slightly emarginate, with three short, blunt teeth. 



Anteunne filiform, joints in order of length 2, 4, 5, G, 1, 7, joints 4-6 

 more or less subequal; olfactory cones 4 or 10. 



Mandibulary stipe with exposed surface divided by sutures into five 

 areas, the basal larger than the others taken together. 



Hypostoma strongly arcuate; rising from each side of the convex 

 median portion is a flattened oblong process lying against depressions 

 of the lower part of the mentum. 



Oardo present, transversely oval. 



Mentum broadly triangular, long pointed in front, very broadly 

 emarginate behind, hirsute. 



Stipes over twice as long as broad, hirsute; lingual lobes large; 

 median lobe n.ot evident. 



First segment subelliptic or subreniform, usually about three times 

 as broad as long. 



Segments with dorsal surface nearly or quite smooth, neither granu- 

 lar nor areate. Along the posterior margin of each segment above is 

 a row of very fine and short longitudinal wrinkles or strii^", usually 

 very distinct under a lens. They occur on the immediate edge of the 

 tergite, at the base of the supplementary margin. 



Lateral carinne moderately or strongly approximate, one-fourth as 

 broad as the body cavity or narrower, inserted from one-half to three- 

 fourths of the height of the body cylinder; lateral margins with a 



'Proc. N. Y. Acad. Sci., 1895, IX, p. 4. According to Saussiire, his genus has the 

 characters of Fontaria with the exception of the pore-formula. The Soutli American 

 forms known to me have not the spine of the second joint of the legs, the most char- 

 acteristic feature of the Xystodesmidie, though the habit is not strikingly difterent. 

 Saussure's statement, however, led me to include Eiirydesmus in the same family with 

 Fontaria, but I now strongly suspect that it is in reality not widely different from 

 Chelodesmus. 



