THE NAUTILUS. 95 



A specimen from Humacao, Porto Rico, which may be taken 

 as type locality, is figured. It scarcely shows growth striae, but 

 the oblique cuticular threads are very well developed, extend- 

 ing upon the base. The umbilicus is contained between 10 and 

 11 times in the diameter. Alt. 2.25, diam. 2.5mm., umbil- 

 icus 0.23 mm.; 4J whorls. 



The specimens from Florida (fig. 3, Fikahatchee Key) are 

 often larger, diam. 3 to 3.2 ram., with the umbilicus slightly 

 larger, 7% to 8 times in the diameter. The sculpture is rarely 

 so perfectly developed (or preserved) as in the Porto Rico 

 shells. It is a common species on the keys and in some places 

 on the mainland, as at Miami and Osprey. 



A single small example from Brownsville, Texas, has the 

 umbilicus remarkably small, contained about 14 times in the 

 diameter. It is more depressed than T. csecoides. It may rep- 

 resent a distinct race, but further material is needed. 



Guppy has recorded the species (as Helix ierensis} from Trin- 

 idad. Specimens are at hand from St. Lucia (Tate), Cariaco, 

 Venezuela (F. R. Cocking) and the U. S. of Colombia (R. Swift 

 coll.)- All of these are rather openly umbilicate, like the most 

 widely umbilicate Florida shells, but not as open as T. 

 fuscula. 



The late Mr. E. A. Smith, in his excellent paper on Trinidad 

 shells (Journ. of Conch. VIII, p. 239), considered plagioptycha 

 and -ierensis synonyms of fuscula Ad., but while the difference 

 is not great, I have been unable to trace a real transition in the 

 size of the umbilicus, and for the present it seems best to recog- 

 nize the distinction. I have seen but three Jamaican speci- 

 mens, however. 



THYSANOPHORA C^ECOIDES (Tate). Fig. 4. 



Helix csecoides Tate, Amer. Journ. of Conch. V, p. 153, Feb., 

 1870. 



Helix guatemalensis Crosse et Fischer, Journ. de Conchyl. XX, 

 p. 222, 1872; XXI, p. 274, pi. 9, fig. 3, 1873; Miss. Sci. Mex., 

 Moll., II, p. 664, pi. 71, figs. 9-96 (Guatemala, Sarg.). 



Acanthinula yranum St.rebel, Beitrag Mex. IV, 18SO, p. 31, 

 pi. 4, f. 13 (Plantage Mirador). 



Yucatan: Progreso (Heilprin Exped. 1890). Guatemala: 



