86 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io» 



Family Turritellidae 



Genus Tachyrhynchus Morch, 1868 



Tachyrhynchus reticulatiim (Mighcls, 1841) 



Plate 5, figure 9 



Turitella reticulata Mighels, 1841, p. 50. — Mighels and Adams, 1842, p. 50, pi. 4, 

 fig. 19. 



A total of 7 living specimens and 3 shells was dredged: 1 living 

 specimen (18.0 mm. high) from 184 feet; 1 (20.5 mm.) from 438 feet; 

 2 living specimens and 2 shells (from 6.7 to 22.3 mm.) from 477 feet; 

 and 3 living specimens and 1 shell (from 10.2 to 17.4 mm. high) from 

 741 feet. 



Other material examined: About 45 specimens from locahties 

 ranging from the Sea Horse Islands to Plover Bay; about 250 from 

 Captain's Bay, Unalaska Island and vicinity; about 60 from the 

 Shumagins and Kodiak Island; 1 from British Columbia; and about 

 100 from localities from Labrador to Casco Bay, Maine. 



Discussion: In all of the Point Barrow specimens the spiral ridges 

 are worn and the ribs are not prominent. The 45 specimens from 

 north of Plover Bay are like the ones from Point Barrow in being 

 worn and in having inconspicuous ribs and spiral ridges, but in speci- 

 mens from Captain's Bay southward, both the spiral ridges and ribs 

 are prominent. In a large lot from Captain's Harbor, the ribs and 

 spiral ridges are so prominent that they give the shell a nodulous ap- 

 pearance. All of these latter shells are smaller than those from more 

 northern waters. Even though worn, about one-half of the speci- 

 mens from localities from Labrador to Maine have the stronger rib- 

 bing characteristic of those from the Aleutians. In a specimen from 

 Greenland the ribs and spiral ridges are not prominent on the last 

 whorls, and in another from Dolphin and L^nion Straits, although less 

 worn than those from Point Barrow, the ribs and spiral ridges are not 

 prominent. 



In this species the spiral bands may be flat and broad with only a 

 narrow groove separating them or they maj^ be higher and narrower 

 with a wider sulcus between. Axial ribs may be very prominent or 

 rather insignificant as in the northern specimens. 



Tachyrhynchus reticnlatum is probably closest to T. erosum (Cou- 

 thouy) but the former is more slender than T. erosum and the latter 

 has no axial ribs (see Morris, 1951, pi. 31, fig. 16; 1952, pi. 26, fig. 9; 

 and Abbott, 1954, pi. 211). The latter also has four or five low, nar- 

 row, rounded spiral striae on tlie base of the last whorl. 



Distribution: Greenland, Labrador, and Nova Scotia to Casco 

 Bay, Mame; Point Barrow and west and south to Bering Sea and 

 east and south to the Aleutians and British Columbia. 



