54 
PATAGONIAN EXPEDITIONS I PALAEONTOLOGY. 
tubercles forming a vertical row of secondaries outside of the main row 
of the ambulacrum. Interambulacral space with 6 vertical rows of sub- 
equal tubercles, to which are added, on the ambitus, two irregular vertical 
median rows of smaller tubercles. Of these six rows the outer and inner 
ones disappear toward the abactinal system. All the tubercles, in both 
the ambulacra and interambulacra, are surrounded by small secondaries 
and miliaries. The median space of the interambulacra appears compara- 
tively smooth toward the abactinal system (as is the case in the recent 
species of the genus). Abactinal system unknown. Actinostome sunken, 
and lower surface concave ; the actinal cuts are comparatively slight. 
Diameter, 48 ; height, 25 mm. 
Diameter, 1 7 ; height, 9 mm. 
Remarks: The large number of vertical rows of tubercles in the inter- 
ambulacral spaces places this species with the genus Toxopneustes. The 
cuts of the actinostome are but slightly developed, but these vary consid- 
erably even in the recent species (see: Agassiz, 1873, p. 498). 
Record of specimens : San Julian, Oven Poin, 3 sp. ; Shell Gap, lower 
horizon, 3 sp. 
Distribution : v. Ihering’s specimens from the bay of S. Jorge, recorded 
by him under the name of Hypechinus patagonictis, may perhaps belong 
to this species. 
Affinities : This genus has not been recorded previously as a fossil one, 
except from subrecent deposits. The present species differs from the re- 
cent species in the larger number of vertical rows of tubercles in the am- 
bulacra, which are much more crowded, and in the shallower cuts of the 
actinostome. The most closely allied species seems to be T. pileolus 
(Lmck.) from the tropical Pacific (see: Agassiz, 1873, p. 497, pi. 8b, f. 1, 2). 
I have compared two young individuals of a Toxopneustes , without local- 
ity, in the Princeton Museum : they seem to belong to T. pileolus. These, 
being of about the same size as the best preserved individual of our fossil 
material, differ only in having 6 vertical rows of tubercles in the interam- 
bulacra, and in the tubercles being a little smaller and not so much 
crowded. The cuts of the actinostome are only slightly narrower and 
deeper in these recent specimens than in our fossil species. 
