MOLLUSOA OF PORTO RICO. 
455 
Acanthoehites spiculosus Reeve. 
Chiton spiculosus Reeve, Conch. Icon., pi. ix, fig. 47,1847. 
Shell elongate-ovate; valves semilunar, rough throughout; blackish brown; ligament horny, 
furnished with thick tufts of bright greenish glassy spiculse. 
Acanthoehites spiculosus var. astriger Reeve. 
Chiton astriger Reeve, Conch. Icon., Chiton, pi. xvm, fig. 109, 1847. 
Shell oblong, rather depressed, not carinated; valves variously colored, often with rather wide 
white stripes on the sides; girdle velvety, olive green, with eighteen large tufts of greenish spicules, 
the periphery having a fringe of spicules. 
Length, 20; breadth, 9 mm. 
Fajardo, Porto Rico; Ensenada Honda, Culebra. Only one variety was collected. 
Acanthoehites hemphilli Pilsbry. 
Acanthoehites hemphilli Pilsbry, Man., xiv, p. 34, pi. xm, figs. 65-67, 1892. 
Animal elongated; the shell narrow, not exceeding one-fourth the total width in alcoholic 
specimens, scarcely carinated, somewhat ovate, truncated behind, brownish red marked with white; 
girdle y>ale brown, roughened with minute scales or spicules, with a fringe of longer white spicules at 
its edge and containing eighteen small tufts of red-brown or whitish spicules. 
Length, 35; breadth, 17 mm. Other specimens are smaller. 
Ensenada Honda, Culebra. 
Class SCAPHOPODA. 
Order S0LEN0CONCHA. 
Family DENTALID7E. 
Genus DENTALIUM Linnaeus, 1758. 
Shell tubelike, .curved, but not spiral, attenuated posteriorly; anterior orifice larger than that at 
the posterior end; dorsal face concave; ventral face convex; no operculum. . 
Subgenus Dentalium: s. s. 
Dentalium g'ouldi Dali. 
Dentalium gouldi Dali, Blake Report, ir, p. 424, pi. xxvi, fig. 4, 1889. 
Shell elongated, slender, slightly or considerably curved; surface polished, sometimes having 
longitudinal microscopic strias, hexagonal throughout most of its length but often round at the 
aperture, the angles pinched up into distinct ribs. Color vitreous or milky white. 
Length, 42; diameter, 2.5 mm. 
Mayaguez Harbor, Porto Rico, one fine specimen and two small ones. 
This has been more or less generally known under the name of D. hexagonum Gould, but it is 
not the original D. hexagonum , which comes from China. 
Subgenus Antalis H. & A. Adams, 1854. 
Dentalium taphrium Dali. Plate 54, fig. 19. 
Dentalium taphrium Dali, Bull. Mus. Comp. Zool., xvm, p. 422, 1889. 
Dentalium taphrium Pilsby & Sharp, Man., xyii, p. 58, 1897. 
Shell small, rather stout, moderately curved, with thirty or more low ribs, those of the dorsal face 
stronger; posteriorly every alternate rib becomes weaker and finally disappears; incremental lines 
close, fine, and sharp. Color pale apple-green. Both orifices are circular. 
Length, 17; diameter, 2.25 mm. 
Mayaguez, Porto Rico, two half-grown dead shells. 
