Mr. R. I. Pocock on the Genus Theatops. 287 



adopted. In support of this it can be shown (1) that Say's 

 description applies well to Newport's specimen in almost 

 every point ; (2) that the only point in which it does not apply 

 is his statement about the absence of the labial teeth ; (3) that 

 Newport's words with regard to the eyes are ambiguous and 

 misleading, and have been wrongly interpreted by subsequent 

 authors. 



Therefore all that is required for the adoption of this second 

 alternative {/. e. that Newport redescribed Say's type) is the 

 assumption that Say overlooked the labial teeth. 



This may well have been so ; for it seems quite likely that 

 he was so accustomed to associate the absence of eyes with the 

 absence of labial teeth that, noting in this case the absence of 

 the former, he without examination took for granted the 

 absence of the latter. 



For the sake of convenience therefore I shall assume that 

 Say and Newport described the same specimen. 



Whatever conclusion, however, be arrived at with regard 

 to this point, the truth of the following statement is beyond 

 all question : — The genus Theatops (Newp.) was recharac- 

 terized in 1862 and again in 1865 (Trans. Amer. Phil. Soc. 

 xiii. p. 169) by Dr. Wood and named Opisthemega. 



That this is so may be demonstrated by comparing the 

 description of Opisthemega taken by Dr. Meinert (Proc. Amer. 

 Phil. Soc. xxiii. p. 207) from Dr. Wood's own specimens with 

 the following description, which 1 have taken from the type 

 specimen of the genus Theatops, which has been preserved in 

 the British Museum ever since the days of Newport. 



Genus Theatops, Newport. 



1844. Theatops, Newport, Trans. Linn. Soc. xix. p. 410. 



1862. Opisthemeffci, AYood, Journ. Acad. Nat. Sci. Pliilad. v. p. 35. 



Capitis lamina laminam dorsi primam partim protegente. 



Lamina basali partim manifesta. 



Oculis uullis vel evanidis. 



Antennis ad basim incrassatis, ad apicem attenuatis ; articulis proxi- 

 mis glabris, reliquis breviter hirsutis. 



Pedum maxillarium sterno integro, in laminas denticulatas antice 

 producto ; articulo proximo dente basali instructo. 



Tarsis tibiisque plerumque calcare armatis ; tarsis plerumque arti- 

 culo unico constantibus, 



Segmcnto anaii segmentis prsecedentibus majore. 



Pleuris analibus truncatis ; maxima ex parte protectis. 



Pedibus analibus maximis, valde incrassatis, articulis quinque con- 

 stantibus ; uugue magno, arcuato armatis. 



Segmeuto corporis septimo spiraculis hand instrueto. 



Spiraculis utriuque novem. 



20* 



