FAMILY ACERID^E BULLA. 19 



Bulla canaliculata. 



PLATE XXXV. FIG. 328. 



Volvaria carmliculata. Say, Jour. Acad. Nat. Sc. Vol. 5, p. 211. 



Bullina id. Id. American Conchology, pi. 39. 



Bulla id. Gould, Invertebrata of Massachusetts, p. 116, fig. 97. 



Descriptio7i. Shell minute, cylindrical, polished, with very faint lines of growth. Spire 

 convex, a little elevated, with a minute but prominent tip : whorls about five, with their 

 shoulders very obtusely grooved. Outer lip arching forward ; inner lip with a thin coat of 

 enamel, with a single oblique fold or small tooth near the base. 



Color. Whitish, immaculate. 



Length, 0"1 - 0'2. 



This species, first observed by Say on the southern coast, has since been found on the 

 shores of Martha's Vineyard. It will, therefore, doubtless be discovered on the coast of 

 New-York. 



This, with B. obstricta, are the only two American species yet observed, possessing a 

 prominent spire. T place the present species here with great doubt, which can only be settled 

 by a minute examination of the animal. 



(EXTRA-LIMITAL.) 



B. solitaria. (Say, Acad. Nat. Sc. Vol. 2, p. 245.) Shell very thin and fragile, pellucid, oval, 

 narrowed at the base, with numerous impressed revolving lines and transverse very obtuse wrinkles. 

 Aperture surpassing the tip of the shell. Spire none, substituted by an umbilicus. No umbili- 

 cus at the base. Length 0-5. Southern coast. 



Supposed by some American writers to be identical with B. insculpta. 



SECTION 4. PULMOBRANCHIA. 



Animals furnished with a foot for crawling. No gills, but instead thereof a pulmonary 

 cavity, receiving the surrounding medium by an aperture on the right side of the mantle. 

 Organs of generation in the same individual, united in the same cavity, or distant. Shell 

 complete, rudimentary or none, external or internal. Without opercle. 



Obs. This section comprises numerous families, extended over the globe. They are ter- 

 restrial or aquatic. Those found in water live at a small depth, as they are compelled to 

 rise frequently to the surface to breathe. They are carnivorous and herbivorous. 



3* 



