MUSEUM OF COMPARATIVE ZOOLOGY. 427 



Also in the Gulf of Mexico, between the delta of the Mississippi and Cedar 

 Keys, Florida, at Station 2402, in 111 fins., mud, by the U. S. Fish Com- 

 mission. 



The posterior half of well preserved specimens is coarsely obscurely striated. 



Dentalium ophiodon Dall. 



Plate XXVI. Fig. 9. 



Dentalium ophiodon Dall, Bull. M. C. Z., IX. p. 38, 1881. 



Habitat. Station 19, in 310 fms. Station 20, in 220 fms. Station 21, in 

 287 fms. Barbados, Hassler Expedition, in 100 fms. 



This is a more slender, smaller, and more delicately striated species than the 

 preceding. 



C. Shell laterally compressed. 

 Dentalium callithrix n. a. 



Plate XXVII. Fig. 10. 



Shell white, moderately curved, laterally slightly compressed ; sculpture of 

 about nine primary longitudinal ridges, angulating the section, with between 

 them toward tbe middle of the shell three to five secondary smaller rounded 

 threads, crossed by moderately strong lines of growth ; the primaries are strong- 

 est posteriorly, they become fainter in front and all the longitudinal sculpture 

 nearly uniform near the aperture in the adult ; aperture oblique, rounded oval, 

 the lower lip in advance, margin thin ; anal orifice circular, simple in the 

 young, without notches or slit ; adults usually show a short broadish slit on 

 the concave side, or are irregularly eroded ; the extreme tip in the young is 

 more curved than the body of the shell, and quite acute. Lon. of shell, 25.0; 

 height of arch above chord, 5.0 ; vertical diameter of aperture, 3.75; transverse 

 ditto, 2.75 ; diameter of anal end in young, 0.25 ; in figured specimen (eroded), 

 1.0 mm. The shell may attain a length of 43.0 mm. 



Habitat. Yucatan Strait, 640 fms. Gulf of Mexico, Station 20, in 220 fms. 

 Station 41, in 860 fms. Station 162, near Guadelupe, in 769 fms., sand, tem- 

 perature 40°.0. Station 221, off Santa Lucia, in 423 fms., ooze, temperature 

 43°.0. Station 236, off Bequia, in 1591 fms., ooze, temperature, 39°.0. Station 

 248, in 161 fms., ooze, off Grenada, temperature 53°. 5. Also at U. S. Fish 

 Commission Station 2678, in 731 fms., ooze, off Cape Fear, North Carolina, 

 temperature 38°.7, and Station 2383, in the Gulf of Mexico, between the delta 

 of the Mississippi and Cedar Keys, Florida, in 11S1 fms., mud, temperature 

 40°.0 F. 



This is a very characteristic species, in which the longitudinal sculpture, and 

 even the shell, are often somewhat spirally twisted as much as one eighth of the 

 circumference. 



