1921] NATURAL SCIENCES OF PHILADELPHIA. 355 



Cymia henekeni Maury. 



L'luna tectum Kiener, Gabb, Tr. Am. Philos. Soc, xv, 1873, p. 214. 

 Cymia woodii (Gabb), in part, Dall, Trans. Wagner Free Inst. Sci., iii, p. 154. 

 Cymia woodii Gabb, Maury, Journ. Acad. Nat. Sci. Phila. (2), xv, p. 82. 

 Cymia henekeni Maury, Bull Amer. Pal. v, p. 104. 



This is a variable species, as the figures given show, but careful 

 comparisons of the series of over 100 specimens with the type of 

 Cymia woodii (Gabb), from the Shiloh Miocene, convince us that the 

 Santo Domingo species is distinct. The Miocene species has more 

 even spiral sculpture, a rounded periphery, and none of the peri- 

 pheral tubercles, which are present on some part of every specimen 

 of henekeni. 



In addition to the generic synonyms of Cymia given by Dall (Tr. 

 Wagn. Free Inst. Sci. iii, 154), we may mention Cumopsis Rovereto, 

 Atti Soc. Ligust. Sc. Nat. e Geogr., X, 1899, p. 105. C. tectum may 

 be taken as type. 



Cymia woodii is probably a derivative from C. henekeni, being the 

 last member of the genus in Atlantic waters. 



Cymia henekeni tectiformis n. subsp. Plate XXVIIl, figs. 11, 12. 

 Cuma tectum Gabb, I. c. in part. 



The shell' is similar to C. henekeni as far as the middle of the pen- 

 ult whorl, where larger tubercles appear at the peripheral angle. 

 On the last whorl there are about 8 such tubercles, those on the back 

 being very prominent and w^idely spaced. Above the periphery 

 there are many spirals, and below it the spiral striation is under-laid by 

 about six low spiral ridges. Dense growth-striae as in C. henekeni. 



Alt. 46, diam. 30 mm. Type; PI. XXVIIl, figs. 11, 12, no. 2794. 



Alt. 45, diam. 32.5 mm. 



A very large specimen, length 54.4 mm., has but six large tubercles 

 on the last whorl. As the tubercles become progressively more 

 widely spaced, the addition of a half whorl to the usual size de- 

 creases the number. 



While the adult stage is conspicuously different, the half grown 

 and young specimens are not distinguishable from C . henekeni. The 

 two forms were mingled in Gabb's collection. 



This form is supei'ficially like C. teciwr/i; but that recent Panamic 

 species differs from all of the fossils by having comparatively few, 

 flat spirals, parted by narrow, deeply engraved grooves. The col- 

 umellar plait also, is heavier and more prominent. 



