Fintay.—Two New Species of Magadina. 533 
bifid. Surface of both valves unsculptured except for growth- — but the 
shell-substance is everywhere elegantly and fairly finely punctate. Thomson 
has not mentioned this as an attribute of M. browni, but it exists in that 
species, though more difficult to observe on aecount of the rubbed surface of 
most specimens; the punctation is slightly vasi a in M. clifdenensis. 
In distinguished also from M. browni by smaller size, narrower and 
ch deeper sinuation, and especially much hatter dorsal valve and more 
convex and very i, А, eatin ventral valve 
Holotype—Length, ; breadth, 7-2 mm. ; thickness, 3:3 mm. 
Paratype— Length, 7m mm.; breadth, 6-6 mm. : thicknes s, З mm. 
nd many pa ratypes, from Clifden, БЫ: bends TA (type) 
and 7B (Hutchinsonian ?)—in author's collection. 
veces thomsoni n. sp. (Fig. 2.) 
M. waiparaensis Thomson (loc. cit., vol. 47, p. 403, 
1915), this species is = described by comparison with one nearly related— 
in this case the previous new species. - From this it differs at sight especially 
in its much smaller size and even flatter dorsal valve, which posteriorly 
is almost perfectly flat and anteriorly deny concave. This fact is due to 
the earlier inception of the median sinus, which noticeably begins to flatten 
the valve at the upper third of the shell and very rapidly e though 
remaining only about half the width of that in M. clifdenensis. At the 
anterior end of sinus the valve is sharply bent in as in that 1 species, but 
Fic. 2. 
T Eros afud a лт ar hinge, giving the shell a subcircular: 
preme AE jadis pointed at both ends. Ventral valve 
very similar to that of preceding species, but more pointed and less raised 
anteriorly, with a similar very strong and blunt but slightly narrower 
carination. Remaining external details, pseudo-deltidium, punctation, &c.,. 
approximately the same in the two species.  Internally the species are 
anterior median ridge separating muscular i D pass is slightly lower. 
Holotype— Length, 5:3 mm. ; breadth, 4-9 mm. ; thic ны, E mm 
Paratype— Length, 5-5 mm. ; breadth, E 7 mm. ; thickn 
Type everal para types, from Clifden, Southend Sand бА 
(Ototaran ?)—in the author's collection. Separa té valves are fairly common, 
but only three perfect specimens have so far Pod obtained ; of these the 
best preserved is taken as the type, though the ventral valve, as the figure 
shows, is bént back a little at margin ; this is due to accident, and normal 
specimens have a regularly convex valve as in M. clifdenen 818. 
The species is named in honour of Dr. Thomson, Director of the Dominion 
Museum, in acknowledgment of much freely-given rane. and аа. 
from its occurrence in older beds, M. thoms shows, in its 
less-developed beaks, its earlier-developed dorsal сне, апі its more 
primitive eardinal process, features that stamp it as ancestral to its near- 
relative, M. clifdenensis. 
