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I I 21 



TERTIARY FAUNA OF FLORIDA 



original list of Scintilla contained a partly heterogeneous assembly, but, until 

 something is known of the anatomy it will be difficult to divide them accu- 

 rately. To determine which portion of the group shall retain the name Scin- 

 tilla it is necessary to proceed by the method of elimination. -S\ Cumingi (=S. 

 cburnca Conrad non Morch) cannot be selected as the type because it was 

 already the type of Solecardia. 



The next work treating of Scintilla is H. and A. Adams's " Genera of Re- 

 cent Mollusca," in which S. philippinensis Desh. is named and figured as an 

 example in 1857, a course followed by Chenu (ii., p. 128) in 1862. This is 

 one of the rather short species, but its hinge agrees with the original diagnosis, 

 though the exterior seems devoid of punctations. It is probable that it will 

 be best to adopt this species as the type. 



In his Manual Fischer figures (after Moebius) Scintilla anrantia (Lamarck 

 as Psaiiunobia, = S. mauritiana Sby., not 5". aurantiaca Desh.) and gives as 

 an example of the genus 5". vitrea Quoy and Gaimard (as Psammobia, = S. 

 aurantiaca Desh. but not 5". vitrea Desh.), but as far as the shells go, the latter 

 of these agrees with S. philippinensis and therefore presents no advantages as 

 type over that species. 



Henry Adams has proposed a genus Barclayia for a species of Scintilla 

 with faintly reticulate surface sculpture, or, rather, a granular surface resulting 

 from the intersection of radial and incremental lines, "but, as this feature is 

 suggested by the surface of 5". Cumingi (=eburnca) when unworn, it is 

 probable that the differential value of this character is not very great. 



The surface of S. ebitrnca (Conrad non Morch) when worn is polished, 

 with minute punctate and divaricate sculpture, but when fresh a large part of 

 the surface is covered with a finely granular calcareous layer which is raised 

 into elevated concentric lines along the incremental sculpture. From this it 

 seems probable that the reflection of the border of the mantle over the valve 

 does not extend so far towards the umbones as in Galcontina. There are also 

 radial impressed lines, especially towards the posterior end, which result in 

 faint serrations of the basal margins of the valves and probably correspond 

 to appendages of the mantle. The cardinal teeth are small and rather variable 

 in form, the ligament elongate and obsolete, the resilium wholly internal, and 

 the hinge-plate deeply excavated. A marked peculiarity is the situation of the 

 subcircular adductor scars entirely within the pallial line, a situation which is 

 probably correlated with the extension of the mantle edge externally. As far 

 as can be judged from separated valves, the ventral gape, when the valves are 

 closed, must be very narrow and mostly posterior. 



