64 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
not suggest a growth from, but rather a piece since inserted onto the 
surface of the saddle. It can only be cited as certainly not against 
the idea that this portion of the jugum is separate in origin from the 
saddle. 
Su.MMARY. 
The subgenus Camarophorella was founded by Hall and Clarke 
in 1894 on a single species from the Kinderhook at Burlington, Iowa, 
Pentamerus Jcnticularis of White and Whitfield. Hall and Clarke 
associated it with the genus Camarophoria in the family Pentameridae, 
the species of which have no brachial support other than the crura. 
Excellent material of a hitherto undescribed species of the same 
genus, C muiabilis, from the Waverly at Scioto\'ille, Ohio, shows the 
incorrectness of the former assignment of the sul)genus and is suffi- 
cient to elevate it to the rank of a genus in the suljfamily ^Nleristellinae. 
The jtigum and its method of formation have not before been de- 
scribed in detail because material sufficiently well preserved, has not 
been obtained. It appears to consist of a H.- or A-shaped saddle 
between the primary lamellae on which the remainder of the jugum 
has been formed as a single plate by a process of spiculization appar- 
ently simultaneous throughout, or possibly by two such periods, 
rather than by a gradual growth of the arms of the structure. The 
resulting jugum is similar in plan to that of INIerista and Meristella, 
although differing in many details. 
The generic characters are re-drawn, the new species, C. viutahilis, 
is described, and the description of C. lenticularis is introduced for 
comparison. 
The probable relationship of Camarophorella to earlier genera is 
considered and a method is indicated by which it could readily have 
been derived from forms like jMerista and Dicamara. Although this 
method is perfectly feasible and there is considerable evidence for it, 
it is nevertheless largely conjectural. The genus is more specialized 
than its supposed ancestors in that the jugum and musculature are 
compacted more closely into the posterior portion of the shell and 
exhibit a closer integration of parts than is found in the earlier 
genera. 
