82 PROCEEDINGS OF THE ACADEMY OP 



guished by tlie single postfrontal. Five other genera have been enumerated* 

 which possess this structure, but none of them have any close affinity with the 

 present. Specifically it resembles the Dromieus calliljemus from Jamaica ; 

 it may also be loosely compared to the Cuban Arrhyton tseniatum. 

 Hab. Cuba. Mus. Smithsonian, Prof. Poly. Coll. 



Arrhyton fulvum. 



Arrhyton tmniatum Cope, Proc. Acad. Nat. Sci. Philad. 1860, p. 421. 



This species differs from the A. t se n i a t u m in its broader head and more 

 acute muzzle. The preocular plate is larger, the postfrontal in contact with 

 the second labial only ; the vertical is shorter, with more convergent outer 

 borders. Temporals six or seven on each side, the anterior as deep as long. 

 The head and body above the third row of scales is deep brown ; the lateral 

 band occupies the fourth and fifth and half the third and sixth rows of scales ; 

 the median the vertebral series alone. In taenia turn these bands are of 

 equal width, occupying one and two half rows. 



Hab. Cuba. Mus. Smithsonian. 



Arrhyton bivittatum. 



Scales in seventeen longitudinal rows. Dentition, as in other species of the 

 genus, strongly diacranterian. Head wider than body, arched in profile, with 

 acute prominent muzzle. Rostral plate visible from above : nasal plates united '! 

 Loreal present, longer than high, rectangular. Preocular plate a little higher. 

 Superior labials seven, third and fourth entering the orbit. Postoculars two ; 

 temporals, three large, two small, anterior broad : the external borders of the 

 vertical parallel. Prefrontals not small. Inferior labials seven ; anterior gene- 

 ials longer. Total length 11 in. ; tail 3 in. 2 lin. 



General color brown ; a blackish band on each side which occupies the adja- 

 cent halves of the scales of the third and fourth rows. 



Hab. Cuba. Mus. Smithsonian, (No. 5784.) 



Monograph of the species of TROGDSITA, inhabiting the United States. 

 EY GEORGE H. HORN, M. D. 



The publication of the present paper was suggested by the neglected condi- 

 tion of the genus. Many American species have been published from time to 

 time by various authors, amounting to about twelve or thirteen, of which Mel- 

 sbeimer (Proc. Acad, ii.) and Pal. de Beauvois, (Ins. d'Afrique et d'Amerique) 

 have published one half, the other half being scattered among various authors. 

 It is to be feared that Beauvois has, from describing insects from two widely sepa- 

 rated parts of the globe, caused confusion by the mingling of specimens. 

 Some of his other American (?) insects remain unknown even now. The pos- 

 session of several of Melsheimer's types enables us to determine their true 

 value with certainty. 



The species here described have been derived in great part from the collec- 

 tion of Dr. Le Conte, with whom all the typical specimens will be found, the 

 collections from other sources serving rather to increase the number of speci- 

 mens than species. 



Our species may be arranged in groups as follows : 



Sec. A. Antennae with the eighth joint equal to the ninth. Species 1 2. 

 Sec. B. Antenn;e with the eight joint much smaller than the ninth : 



1. Sides of thorax sinuate or rounued, strongly emarginate before 

 the posterior angles, which are acute. Species 3 6. 



2. Thorax subquadrate, sides moderately rounded, posterior angles 



acute. 



a. Convex Species 7 10. 

 6. Depressed Species 11 13. 



* Proc. Ac. Nat. Sci. Phil. 1861, pp. 302, 524. 



[Feb, 



