PLATE V 



Figure 1, 2. Unio spinosus, Lea. 



"Testa spinosa, subtriangulari, inflata, insquiiaterali, postioe acuto-angulala ; valvulis suboras- 

 sis; clivo umboniali carinato ; natibus vixprominentibus ; epidermide atro fusca, glabra; dentibus 

 cardinalibus deorsuin inclinantibiis ; lateralibus suhgrandibus subcurvisque ; margarita purpurea." 



Trans. Amer. Phil. Soc. vol. vi. p. 57, pi. xvi. 



Habitat, Allamalia River, Hopeton, near Darien, Georgia ; also Liberty County, 



Georgia. 



"Shell spinous, subtriangular, inflated, inequilateral, acutely angular be- 

 hind ; arcuate on the dorsal margin ; substance of the shell rather thick, 

 thinner behind ; spines erect, opposed in each valve, placed in a row before the 

 umbonial slope, and nearly parallel thereto ; umbonial slope carinate ; beaks 

 scarcely prominent ; ligament short and thick ; epidermis dark brown, shining, 

 finely wrinkled ; cardinal teeth inclining downwards, single in the right and 

 double in the left valve ; enlarged and truncate at the anterior end ; lateral teeth 

 rather large, thickened and curved in the inferior portion ; anterior cicatrices 

 distinct; posterior cicatrices confluent; dorsal cicatrices placed in the inferior 

 part of the cardinal teeth ; cavity of shell deep ; cavity of the beaks angular ; 

 nacre purple." 



Mr. Lea also observes, in his interesting details of this shell, that "the teeth 

 difier in some of their characters from any Unio with which I am acquainted. 

 The highest part of the dorsal curve is equi-distant from the extreme ends of the 

 two teeth. The cardinal teeth are remarkable for their form and position, being 

 very much enlarged at the anterior end, and pointing to the anterior margin. 

 The lateral teeth are lamellar, and unusually enlarged on the inferior portion, 

 thus forming an inverted curve, the inferior portion of the double lamellar tooth 

 being very much larger than the superior one. The nacre of the shell is purple, 

 approaching a rose color, and is very beautiful." 



The specimen in ray Cabinet is a very perfect young shell, with only two per- 

 fect spines, one on each valve, and exactly opposite. These spines are hollow, 

 and on the interior of each valve, and immediately underneath the spines, there 

 is, in my specimen, a covered canal running towards the anterior margin, and 

 into which a bristle may be inserted for half an inch. Whether this canal com- 

 municates with the external spines I cannot say ; but it appears to me to be very 

 probable. I am indebted to Major Leconte, of this city, for the beautiful specimen 

 in my Cabinet. The figure is a copy of Mr. Lea's plate. 



