Mr. R. I. Pocock on the Genus Theatops. 289 



Assuming this to be the case, his statements become intelli- 

 gible, for when examined with a lens of low power the head 

 appears to be furnished upon each side with a single ocellus. 



Although Dr. Wood in his descriptions of Opistheinega 

 postica and of Op. siiinicauda makes no mention of the 

 presence in these species of any eye-structures resembling 

 those described above, yet Dr. Meinert, when characterizing 

 the genus Opisthemega, remarks : " Oculi nulli vel evanidi." 

 But since the latter author omits to state in which of the 

 species described by him the eyes are " evanidi," it is fair to 

 presume that he attaches no specific value to the features pre- 

 sented by these organs. 



It is certainly to be regretted that a genus composed of 

 species in which the eyes are either absent or rudimentary 

 should be known by a name so inappropriate as Theatops. 

 Yet the law of priority compels its adoption, and one's regret 

 is perhaps to a certain extent lessened by the satisfaction de- 

 rived from abolishing a name so ill-formed and so ill-sounding 

 as Opisthemega. 



Theatops postica (Say). 



1821. Cryptops postica Say, Journ, Acad. Xat. Sci. Pbilad. ii. pp. Ill, 



112. 

 1844. Theatops postica, Newport, Trans. Linu. Soc. xix. p. 411. 

 1862. Opisthemega postica, Wood, Journ. Acad. Nat. Sci. Philad. v. 



p. 35. 

 1886. Opisthemega crassipes, Meinert, Proc. Amer. Phil. Soc. xxiii. 



p. 200. 



Dorsal plates ochraceous ; head-plate castaneous j antenna}, 

 ventral plates, and legs testaceous. 



Head, body-segments, and anal legs strongly punctured. 



Antennai consisting of 17 segments. 



Distal segments of the antennse more or less moniliform 

 and covered with short hairs. Basal segments bare. 



Prosternal plates of the maxillary sternum almost in con- 

 tact ; each armed with three small obtuse teeth. Basal tooth 

 small, obtuse and simple. 



Dorsal plates, except the first and last, bisulcate ; the first 

 marked in front with a median longitudinal sulcus, which 

 behind bifurcates and marks off with the posterior margin of 

 the dorsal plate a triangular area. Dorsal plates, except the 

 last, with simple margins. 



Head-plate without sulci. 



Ventral plates marked with a central longitudinal depres- 

 sion, the last elongated, with converging lateral margins. 



