84 



Genus Stricklandia. (Billings.) 



Stricklandia, (Billings) Canadian Naturalist and Geologist, Vol.4, p. 434, April, 1859. 

 Rennsel^kia, (Hall) pars. Twelfth Annual Report of the Regents of the State of New 

 York, p. 39, October, 1859. 



This genus was proposed by me, in the work above cited, to include 

 such shells as those known in England under the names of Pentamerus 

 lens, P. liratus, and P. loevis. They differ from Pentamerus in having 

 the valves usually sub-equal, and no longitudinal septa or triangular 

 chamber in the interior of the dorsal valve. Both valves have an area, 

 but in the dorsal it is usually linear, or only slightly exceeding the thick- 

 ness of the substance of the shell in height. The ventral valve has usually 

 a concave mesial sinus more or less developed, and the dorsal valve a 

 mesial fold corresponding thereto. The hinge line in some of the species, 

 such as in S. loevis and iS. micro eameruSy have the hinge line straight and 

 much extended. 



Among the brachiopoda found in the limestone nodules of Point L^vis 

 there are two species which have all the internal characters of this genus. 

 The form is also the same, except that in one of them, S. AracJme, the 

 area of the ventral valve is so much developed as to give the whole shell 

 the external appearance of an Orthis. It has, however, the mesial fold 

 and sinus, and the shell exhibits a tendency to vary, by the extension of 

 the middle of the front margin, which is also a pecuharity of the typical 

 species. De Verneuil has described in the Geology of Russia, vol. 2, p. 

 129, PI. 2, fig. 1 a-g, a species vmder the name of Spirifer Tcheffkini, 

 which appears to me to be a Stricklandia , and to stand between S. Arachne 

 and S. brevis. The surfaee is reticulated in nearly the same way, and the 

 form (in a general sense,) is similar, with the exception that the ventral 

 area is very slightly developed, or almost linear. Judging from the exter^ 

 nal characters alone, for the interior is not described, I should say that S. 

 Tcheffkini belongs to Stricklandia. Should this surmise turn out to be 

 well-founded, then these three : S. Arachne, S. Tcheffkini, and S. brevis 

 will fonn a very complete series, leading to S. lens, S. Gaspcnsis and 

 others, which constitute the bulk of the genus. I strongly suspect that 

 Carrier ella Calcifera should be referred to Stncklandia. 



