336 



PROCEEDINGS OF THE ACADEMY OF 



[May, 



Holospira bilamellata Dall. Plate VII, figs, l to id. 



Holospira {Didomospira) bilamellata Dall., Proc. U. S. Nat. Mu.s., XVIII, 

 1895, p. 4; XIX, p. 896, p. 349, PL 31, fig. 3. Pilsbry, Man. of Conch., 

 XV, 1902, p. 82, PI. 16, fig.s. 5, 10, 11. Bartsch, Proc. U. S. Nat. Mus. 

 XXXI, 1906, p. 134. Daniels, Nautilus, XXVI, p. 41, PI. 5, fig. 9 (normal) 

 and fig. 8 (abnormal) shells. 



The first four references cited above pertain to specimens of tlie 

 original lot, of which there are 8 perfect shells in Coll. U. S. Nat. Mus. 

 and 2 in Coll. A. N. S. Phila. 



The species is distinguished from H. crossei chiefly by its greater 

 size. It was found by Mr. Daniels and the writer in great abundance 

 at Station 5, on the east side of Daniels Mountain under the cliffs 

 ■close to the summit, with Ashmunella niearnsi and Oreohelix, in the 

 piiion zone. In most of the shells the external ri!)s weaken or dis- 

 appear on the penultimate and one or two earlier whorls, but in 

 some they continue to the last, as in the type lot of bilamellata. 



Sixty examples from Station 5 opened, most of them measured 

 ^ive the following data: 



(1) One lamella, the axial. 13 specimens — 21f %. 



(2) Two lamellae, axial and basal. 41 specimens = 685%. 

 Length 2.2, diam. 4.9 mm. ; whorls ISh 



