51 
To follow Stoliczka’s interpretation of ^urydesma it Avould be necessary 
to regard the genus as possessing a slight anterior gape/ hnt Waagen says, 
“ there does not exist a trace of such a gape, the valves being perfectly 
closed in front in the manner figured by Dana in Eurydesma (jlohosum, 
Dana.”^ 
6. Limule . — The anterior cordate depression lielow the umbones is large 
and deep, and in position corresponds to the lunule of other Pelecypoda. It 
is not circumscribed by ridges, but its whole surface is roughened by the 
laminar structure of the test. These laminse are crowded together in the sub- 
umbonal region, and are no longer visible externally ; but in the left valve, 
at least, they roughen the upper or protruding surface of the cardinal fold. 
A similar, but more contracted, lunule-like depression in Meleagtina is 
eipially lamellate. Analogous structures also occur in other genera, as Dali 
remarks : — “ In Vnio, for instance, in most species is a 
depressed space, homologous with the lunule of Venus, over which the 
epidermis is raised in dense elevated lamellae.”* 
The earlier writ(>rs also referred to this region. Stoliczka, in his brief 
notice of Eurydesma, referred it to the Tridacnidae, partly on the supposed 
existence of an “ excavate and gaping lunula.”^ Waagen, on the other hand, 
denies the presence of “ a gaping lunette,”"’ although, in describing 
E. globosum, Waagen, he refers to “ a distinct emargination in the strongly 
sloping outline which corresponds to a kind of lunula situated in front of the 
apex, and very deeply excavated.”® But this is a different interpretation to 
that of Stoliczka. 
In speaking oP the same species, Waagen also says : — “ Yet more for- 
ward there extends the deeply excavated anterior lunula, 
characteristic of the genus, and reaching half-way down to the anterior 
margin of the shell.” ^ In the left valve of the same species, “ in front of the 
apex, there extends here a large, smooth, well-excavated lunula, the cardinal 
margin of which projects vertically strongly in a semi-elliptical curve, and 
'Stoliczka — Cret. Fauna S. India, IV, Pts. 5-8, 1871, p. 1.37. 
’Waagen — Salt Range Fossils, IV, Pt. 2, 1891, p. 1,37. 
’Dali — Trans. \Vagner Free Inst. Sci., 1895, III, Pt. 3, p. 501. 
’Stoliczka — Cret. Fauna S. India, III, Pts. 5-8, 1871, p. 226. 
® Waagen — Salt Range Fossils, IV, Pt. 2, 1891, p. 137. 
‘Waagen — Loc. eit., p. 138. 
’ Waagen — Loc. cit., p. 139. 
