54 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 109 



separated from the separanda group in spite of some superficial simi- 

 larities between the less specialized members of the two groups. When 

 viewed mesially, the telopodite arcs of the gonopods of the members 

 of this group tend to curve cephalically, though the more primitive 

 species show this condition only slightly. 



The type of the genus, B. ochra initialis, has gonopods but little 

 advanced over the basic type. The curvature tends only slightly 

 cephalically. The sharp bend in the telopodite is distinctive. Ap- 

 parently cedra and electa are derivatives of the ochra line. Both show 

 indications of the same kind of telopodite bend as that occurring in 

 ochra. B. tenehrans, though highly specialized, is easil3" derived from 

 an ocAra-like ancestor by modification of the distal portion of the 

 telopodite and increase in gonopod size. The sharp bend and shoulder 

 of ochra and cedra is still retained in tliis species. 



Slightly advanced over the ochra group and lacking the sharp bend 

 in the telopodite is indianae. In this species the curvature of the 

 telopodite typical of this second major branch of the genus is very 

 pronounced. The general form of the gonopods still somewhat re- 

 sembles ochra. The gonopods are stUl small as are those of ochra, 

 cedra, and electa. It woidd seem that indianae arose from* the early 

 ochra line before the sharp bend had arisen in the latter species. 



This branch of the genus apparent!}^ led to a group of species with 

 heavy, bulky, complex gonopods. Speculations regarding relation- 

 ships Avithin this group are exceedingly difficidt inasmuch as there are 

 many conflicting matters to consider. Characters that must be con- 

 sidered include the size and bulk of the gonopods, the presence or 

 absence of a solenomerite, the presence or absence of a terminal plate, 

 the relative length of the postcingular portion of the telopodite, and 

 the complexity of the form of the gonopods. Which of these charac- 

 ters is more important as an indication of relationships is unknown. 

 Since different conclusions can be reached depending on which char- 

 acters are stressed, it must again be emphasized that the possible re- 

 lationships shown in the accompanying diagram are open to much 

 question. 



The three species viridicolens, kentuckiana, and calceata have much 

 smaller gonopods than do the other members of this group. This 

 would seem to indicate that they are more primitive. In most of the 

 other characters mentioned above, however, they are much advanced 

 and apparently highly specialized. Another species, Hgula, has much 

 simpler, less bulky gonopods but they are considerably larger. In 

 this instance I believe it probable that small gonopods have been 

 maintained from the earl}^ ochra-indianae stock and that those species 

 such as Hgula, splendida, laminata, and hojfmani Avith larger gonopods 

 have each independently evolved this characteristic. 



