12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



postoccipital sutures anteriorly along the ventral aspect as the gular 

 sutures (gs). The result is a gular sclerite which is narrow between 

 the postgenae, expands posteriorly along the ventral edge of the 

 foramen magnum, and is continuous with the submentum anteriorly 

 at the line of the tentorial pits. Posteriorly the gula closes the base 

 of the foramen magnum and is in close contact with the cervical 

 sclerites. 



The anterior portion of the ventral asi^ect of the cranium bears on 

 its inner surface a thickening or ridge known as the crassa (fig. i A, 

 cr) (MacGillivray, 1923). This ridge extends from the region of the 

 maxillary articulation to the mesal side of the ventral articulation 

 of the mandible, and it is presumed to function as a support of this 

 latter structure. Stickney ( 1923) interprets this as the occipital suture, 

 and if this interpretation is correct, the ridge would be properly called 

 the hypostomal ridge. 



A number of other sclerites are present on the head of many 

 beetles, but they are small and relatively unimportant. The oculata 

 (fig. I E, o/) is a wide ringlike shelf on the inside periphery of the 

 eye. There is apparently in this species no sclerite that can be identi- 

 fied with the antennal sclerite, which is normally situated within the 

 antennal fossa. 



Certain parts of the head capsule are modified to form rather 

 definite condyles for the movable parts. These are of considerable 

 importance because they are usually very definite and permanent in 

 position and are thus very useful landmarks for identifying the other 

 parts. The antenna generally articulates with the head by means of 

 an obscure sclerite, the antennal sclerite, mentioned above. This has 

 not been observed, but the condyle is probably present in some form 

 as an articulating surface. The mandible articulates with the head by 

 means of two condyles, forming the dorsal (fig. 2 J, iimd) and the 

 ventral (fig. 2 F, mav) articulations. The dorsal articulation is formed 

 by a rounded protuberance, situated in front of the eye at the antero- 

 lateral corner of the head, which fits into an hemispherical acetabulum 

 on the mandible. The ventral condyle is situated on the mandible 

 and articulates with an acetabulum at the anterior end of the crassa 

 (cr). The articulation of the maxilla is a small condyle on the mesal 

 end of the cardo, which articulates in a small concavity on the inner 

 face of the postgena at the mesal end of the crassa (cr) . In the present 

 species this condyle is undeveloped and is not actually in contact with 

 the postgena. 



The median anterior part of the lateral aspect of the head is oc- 

 cupied by the compound eye (fig. i E, c). This organ is ovate in 



