82 MAZATLAN BIVALVES 
115. P CIRCE SUBTRIGONA, 2. s. 
C. t. parva, subtrigond, postice longius, margine ventrali 
ovali; concentrice tenuissime striatds; wmbonibus ap- 
pressis, subrugosis ; ligamento celato ; dentibus lateralibus 
posticis magnis, anticis subapproximatis ; impressionbus 
muscularibus 4 margine distantibus ; albo-lutescente, macula 
uscd postice, intus subrugosé, et linets divaricatis huc et 
alluc pictd ; epidermide tenut. 
Known at once from C. margarita by its shape which is 
longest behind ; by the very fine concentric strie; the large 
posterior tooth (not so large however proportionally as the 
anterior tooth of C. margarita;) and the painting, which dis- 
plays a large irregular brown patch inside, which projects 
somewhat above the regular level and is slightly rugose, and a 
few irregular zigzag lines on a yellowish white ground. I have 
not been able to trace the pallial line. There is no trace of 
sinus, though the colour markings sometimes give an erroneous 
appearance of it. In other respects the generic characters are 
satisfactorily marked. It is somewhat less uncommon than 
C. margarita, though I found very few fresh specimens. This 
greatly exceeds it in size. Long. °08, dat.‘ 11, alt. °04. 
Hab.—Mazatlan ; on Spondylus Lamarckii, rare; L’pool Col. 
Tablet 413 contains 2 minute valves, cardinal teeth not 
formed; 2 adolescent and a pair united; and 2 valves adult. 
Genus GOULDIA, C. B. Adams. 
As I have neither had the good fortune to find the original 
diagnosis of this genus, nor to meet with any conchologist who 
understood it, 1 can only guess what it was meant to include. 
The late learned and very accurate Prof. Adams, in his descrip- 
tion of the following species, gives no account of the teeth. 
Fortunately however Mr. Cuming possesses and has allowed me 
to examine type specimens of G. parva and Pacifica, received 
from the Professor. The former bears a general resemblance 
to our ? Circe minima: the second is undoubtedly the Mazatlan 
shell, and is like an Astarte with lateral teeth, such as occur in 
not a few of the Crag species. A third species is now added, 
from its general agreement with the second. 
