220 SUBULINA. 



no doubt, considerably more in perfect examples) ; last whorl 

 rounded in the periphery, somewhat concavely attenuated 

 and produced at the base. Aperture distinctly oblique, asym- 

 metrically ovate, acute above, regularly arcuated at the 

 outer side, sinuous in the form of an S on the columellar 

 side, rounded at the base; external margin thin, simple, 

 arcuate; columellar margin formed by a strong, thick, white, 

 spirally twisted line, which enters above into the interior of 

 the aperture, and is terminated at the base by a vertical 

 narrow notch. Length (of the injured shell) 11 mm., diarn. 

 including the aperture 3, diam. of the penultimate whorl 

 2i/2 ; aperture 2y 2 mm. long, iy 2 broad. Last whorl, seen 

 from the dorsal side, one-third of the length of the six 

 preserved whorls united." (v. Mts.). 



E. Guatemala: Panzos (Conradt). 



Tornaxis singularis MARTS., Biol. Centr. Am. Moll., p. 311, 

 pi. 18, f. 6 (April, 1898). 



"In the unique specimen the costae are rubbed down here 

 and there, and the hole of the upper breach is open, which 

 proves that the upper whorls have not been lost during life." 



Genus SUBULINA Beck, 1837. 



Siibulina BECK in part, Index Moll. p. 76. HERRMANNSEN, 

 Indicis Gen. Malac. ii, p. 522 (Feb. 1849). GRAY, P. Z. S. 

 1847, p. 177, 178, and of most modern authors. Macrospira 

 SWAINSON, in part, Shells and Shell-fish, p. 335, for octona 

 auct. and apcrta Gldg. (1840). Stenogyra, Achatina and 

 Bulimus of older authors. 



For generic description see p. 71. In America Subulina 

 inhabits nearly the whole tropical region, but there are very 

 few species. 



The shell is very similar to that of the agnathous group 

 Pseudosubulina, but the latter is generally more strongly 

 sculptured with vertical riblets. 



Subulina differs from Homorus by its clear, more or less 

 li-nnsparent shell, without dark streaks, and by the generally 

 smaller size and narrower contour. It must be admitted that 

 at present the two groups are retained as separate genera, on 



