Occasional Papers of the Aliiseiiin of Zoology 9 



istic form of the collum of the latter. It resembles more nearly 

 S. giiianana, though a notably narrower form, standing apai t 

 in lacking the low keel prominence or ridges of the latter spe- 

 cies. The rostrum is shorter in comparison with the length of 

 the legs, and the head also proportionately a little shorter. 

 (See PI. 3, Figs. 21, 22.) Collum of similar form. 



Also different from giiiauana in the form of the pleurites. 

 Anterior pleurites typically as shown in PI. 3, Fig. 23. Poste- 

 rior pleurites as shown in PI. 4. Fig. 24. 



Xumber of segments, 62. 



Length, 19 mm.; width, 1.8 mm. 



British Guiana: Sand Hill Forest: Aug. 24, 1914; F. M. 

 Gaige. One female taken in Calladium root mass. Holotype, 

 M. C. Z.. 5.052. 



POLYZONIIDAE 



Siphonotus parvus, sp. no v. 



PI. 4. Figs. 28. 29 



Dusky brown above anteriorl\-, lighter brown caudally. 



In comparison with the West Indian S. purpureus Pocock 

 this is a much smaller form, having fewer segments and much 

 broader relatively to its length. Head in its form, position of 

 eyes, and form of antennae nearly as in that species. (See 

 PI. 4, Fig. 28.) 



The two forms appear to be distinguishable by differences 

 at the caudal end of the body. In parziis the penult tergite 

 completely covers the anal tergite. excepting for the tip of 

 Cauda, and in lateral view the middorsal line appears convex, 

 bending down more of caudal border, longer relatively to the 

 preceding tergite ; in piiipurciis the cauda is considerably 

 exposed and the dorsal line of penult tergite in side view is 



