﻿QUADRATE. 



105 



under the name of T. Parkinsoni (' Trigonies,' tab. x, fig. 6), but he avows his 

 uncertainty as to the correctness of this identification. Judging from the drawing upon 

 the plate of Agassiz, it is not identical with any known British species ; of its several 

 features the general form alone possesses any similarity to the section of the Quadrata 

 in which that author placed it. 



Three years after the publication of the memoir of Agassiz D'Orbigny figured and 

 described the large Le Mans shell for the T. dcedalea of Parkinson ( f Paleont. Fran., 

 Ter. Cret./ vol. iii, p. 45, plate 292). 



Our wood engraving exemplifies T. quadrata, kg., or T. dadalea, D'Orbigny ; the 

 original is one of a fine series in the British Museum, numbered 32,394 ; it is remark- 

 able for the great length of the siphonal border, which exceeds that of the upper border 

 of the valve ; the absence of any row of nodes at the carinal angle of the valve, the more 

 numerous and smaller rows of pallial nodes, their general confusion, or, in other 

 instances, the attenuation and crowded bifurcation of the rows near to the pallial border, 

 the simple curvature of the few first-formed rows, and the general absence of any 

 distinct separation between the pallial and siphonal portions of the valve, supply very 

 evident distinctive differences. The valves of T. quadrata are also more depressed, 

 more thin, their surface ornaments are much less prominent than in T. dadalea, their 

 condition of preservation is also less satisfactory ; not un frequently large portions of 

 their surfaces are deprived of the test or have the ornaments imperfectly preserved. 



