104 DENTALIUM-L^VIDENTALIUM. 



b'. Smaller ; tube flattened on concave side ; length 36 

 mill., about 14 times the diam., insolitum, p. 109. 



b". Smaller; tube slightly compressed vertically; much 

 tapering ; length 37 mill., about 12 times the diam., 



leptosceles, p. 110. 

 D. PERLONGUM Dall. PI. 18, figs. 10, 11. 



Shell solid, opaque white, shining, without sculpture, except deli- 

 cate irregularities due to incremental lines ; oral aperture simple, 

 nearly circular, its plane quite or nearly at right angles to the axis. 

 Anal aperture with a shallow notch (in adult specimens) on the con- 

 vex side; tube very slightly curved. Length 50 to 80 mill., oral 

 diam. 3-5 mill. ; anal diam. 0'5 to 0'7 mill. (Dall). 



Yucatan Strait, 640 fms. ; off Guadelupe in 734-769 fms. ; of St. 

 Vincent in 424-785 fms. ; off Bequia in 1507-1591 fms. ; off Grenada 

 in 792 fms. (Blake). Off Cape Hatteras, N. ., in 683 fms. ; Gulf 

 of Mexico, between Mississippi delta and Cedar Keys, Fla., in 227- 

 1191 fms. ; Florida Keys; also 90 miles north of Gear a, Brazil, 1019 

 fms. (Albatross). 



Dentalium perlongum DALL, Bull. M. C. Z., ix, p. 36 (July, 1881) ; 

 Ibid., v, p. 61, 1878 (no description); Ibid., xviii, Blake Moll, p., 

 419, pi. 27, f. 6; Bull. 37, U.S. Nat. Mus,Catal. Mar. Moll. S.-E. U. 

 S., p. 76, pi. 27, fig. 6 ; Proc. U. S. Nat. Mus., xii, p. 294. DALL in 

 Agassiz, Three Cruises of the Blake, ii, p. 67, f. 284 (1888). 



This fine species has been carefully compared with all those from 

 deep water in the Jeffreys collection, and seems fully distinct from 

 any of them. Mr. Watson observes that the young resembles D. 

 longitrorsum Reeve in texture and general appearance, but is 

 straight. D. acutissimuw, Watson is stouter and more curved 

 (Dall). 



The fissure is Antalis-like ; our figure 11 was drawn from one of 

 the types. 

 D. CAUDANI Locard. PI. 18, fig. 12. 



Shell relatively very large, of a very narrowly conoidal form, much 

 elongated and progressively attenuated, feebly arcuate a little past 

 the moiety of the length ; shell quite thin, smooth and glossy 

 throughout, showing only fine, crowded, irregularly and slightly ob- 

 lique concentric growth lines ; aperture very obviously oval, slightly 

 oblique ; apical fissure narrow and short ; color grayish-white. 

 Length 105, diamete.r of aperture 9, at apex 1 mill.; curvature 9 

 mill. (Locard). 



Gulf of Gascony, 1300 meters (Caudan Exped.). 



