304 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 31) See. 



Dynamene glabra Richardson. 



Dynamene glabra Richardson, Proc. U. S. Nat. Mus. v. 21, p. 834, fig. 11, 

 1899. 



Specimens of this species were collected at Mendocino 

 County, California, and at San Diego, California. The 

 emargination of the caudal shield in this species is shallow 

 and the caudal shield is very similar to that found in some 

 species of SfhcBrotna. In Sphceroma rkomburum Richard- 

 son the sides of the caudal segment are folded down, form- 

 ing a sort of groove on the lower side as in the present 

 species. In Sfhmroma octoncum Richardson there is a 

 similar groove on the lower side of the shield and the apex 

 is almost emarginate. In the females of Dynmnene scul^ta 

 the posterior sinus is often very shallow, so that the genus 

 Dynamene seems connected with SfhcBroma by various 

 transitional stages. Dynamene glabra shows a noteworthy 

 point of agreement with S-phceroma in that the sexes do not 

 show the marked dimorphism found in the two preceding 

 species. An examination of several specimens of this 

 species showed that the males present no appreciable 

 external differences from the females except that, as a 

 rule, they are of somewhat larger size. 



University of Michigan, 



Ann Arbor, Michigan. 



