MARYLAND GEOLOGICAL SURVEY 239 



TURRTTELLA VARIABILIS VAR. 



Plate LYII, Figs. 6, 7, 8. 



In addition to the varieties already described, there are in the Calvert 

 formation several other forms which perhaps would be as worthy of retain- 

 ing names as those already discussed. But the variation in this species 

 is so extreme that it seems unwise to give additional names without 

 stronger reasons than at present exist. 



Yar. A. — Much elongate, whorls with an elevated carination near the 

 lower suture, surface concave on either side of the carination. There is 

 a peculiar form from Skipton in the TJ. S. National Museum which re- 

 sembles this, and which is labelled " T. terstriata Rogers." 



Yar B. — Much elongated, whorls strongly convex, sculpture almost ob- 

 solete. 



Var. C. — Whorls flat, sculpture obsolete. 



Occurrence. — C»alvert Formation. Plum Point, Chesapeake Beach, 

 3 miles south of Chesapeake Beach, Truman's Wharf, White's Landing, 

 Fairhaven. 



Collections.— Maryland Geological Survey, Johns Hopkins University, 

 TJ. S. jSTational Museum. 



Genus TACHYRHYNCHUS Morch. 



Tachyrhynghus perlaqueatus (Conrad). 

 Plate LVII, Fig. 9. 



Turritella perlaqueata Conrad, 1841, Proc. Acad. Nat. Sci. Phila., vol. i, p. 33. 

 Tnrritella perlaqueata Conrad, 1843, Jour. Acad. Nat. Sci. Phila., vol. viii, 1st ser., 



p. 189. 

 Turhonilla perlaqueata Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. .566. 

 Tnrritella perlaqueata Meek, 1864, xMiocene Check List, Smith. Misc. Coll. (183), 



p. 16. 



Description. — " Subulate ; whirls convex at base, longitudinally ribbed 

 or fluted, with very fine spiral striae, most profound towards the base of 

 the larger volution. Length rather more than half an inch." Conrad, 

 1841. 



Length, 13.5 mm. ; diameter, 4.5 mm. 



Occurrence. — Calvert Formation. Plum Point. 



Collections. — Philadelphia Academy of Natural Sciences, U. S. Na- 

 tional Museum. 



