72 PROCEEDINGS OF THE ACADEMY OF [Feb., 



mentioned paper). Observe that this only occurs in those species 

 with double frontal grooves. 



The following is an explanation of the figures given in the plate, 

 which are camera lucida tracings, the details being filled in as accu- 

 rately as possible. I believe them to be true representations of the 

 specimens from which they were made, the accuracy centering upon 

 the ridges and grooves, and are representative of Mr. Hayward's 

 groups, as follows : 



Figure 8, Group XII, B. vile, drawn from a specimen collected 

 at San Diego, Cal. From its general facies it is usually placed in 

 collections with individuals of Groups XIV or XVII. An exam- 

 ination of the frons and other group characters wuU readily dis- 

 tinguish it. 



''Frontal grooves single, parallel." The single ridge of either 

 side terminating anteriorly at apex of the frontal process of the 

 corresponding side, not passing on to the epistoma, posteriorly 

 becoming attenuated and disappearing near the posterior border of 

 the eye and bearing upon its convexity the supraorbital setigerous 

 punctures ; ocular bead well developed ; ocular sulcus narrow and 

 normal ; internal grooves normal. 



Fig. 2, Group XIII, B. hijasciatum, drawn from a large speci- 

 men collected at Poway, San Diego county, Cal. 



"Frontal grooves single, parallel." Frons broad, feebly convex, 

 disposition of grooves and ridges as in Group XII. Anterior 

 supraorbital punctures in large shallow fovese. Ocular bead and 

 sulcus well developed and normal. 



Fig. 5, Group XV, B. affine, drawn from a specimen collected 

 in Virginia. 



"Frontal grooves slightly oblique, the outer interrupted." The 

 obliquity being so slight and the ridges not extending on to the 

 epistoma, I believe it to be next in the evolutionary series. 

 "^ The anterior fovese have extended backward and forward, separ- 

 ating the two lateral moieties of the single ridges, forming the first 

 rudiments of the interrupted extei-nal groove of Hayward. The 

 disposition of the sculpturing is nearly as in Group XII — i. e., no 

 extension on to the epistoma; ocular bead and sulcus fine but other- 

 wise normal. 



"" Figs. 3 and 6, Group XIV, B. J^-maculatum and B. duhitans. 

 The former drawn from a specimen collected in Massachusetts ; the 

 latter from a specimen collected near Portland, Ore. 



