ORTMANN : TERTIARY INVERTEBRATES. 
51 
SYSTEMATIC PART. 
ECHINODERMATA. 
Echinoidea. 
Fam. CIDARIDsE Wright. 
Gen. CIDARIS Klein. 
1. Cidaris Antarctica Ortmann. 
PL XI, Fig. i a d . 
1900 Cidaris antarctica Ortmann, in: Amer. Journ. Sci., v. 10, p. 369. 
Only isolated interambulacral plates and spines. 
Plates with a moderately large, perforated central tubercle, the neck of 
which is slightly and indistinctly crenulated. Scrobicule large, surrounded 
by a circle of small tubercles, between which there are, irregularly scat- 
tered, still smaller ones. Spines subcylindrical, mostly slightly compressed, 
so as to render the cross section elliptic ; neck somewhat constricted. For 
the rest, the different fragments are of about the same thickness through- 
out their length. Articular surface conical, finely striated, with a deep 
articular groove. Surface of spines closely covered with fine, rounded 
granules, forming irregular longitudinal rows. The granules are evenly 
developed all around the spine : but there are four spines from Lake 
Pueyrredon, which show larger, irregular, conical, subspiniform tubercles ; 
in two of them these tubercles are found only on one side of the spine. 
Record of specimens : Mouth of Santa Cruz River, 8 spines ; San Julian, 
Oven Point, 1 spine, 1 plate ; San Julian, Darwin Station, 3 spines ; 30 
miles north of Rio Chalia, 4 spines, 5 plates ; Lake Pueyrredon, base of 
Tertiary, 17 spines, 3 plates. 
Affinities : Similar spines are known in Cid. avenionensis Desm. (Mio- 
cene of France and Switzerland, see: Loriol, 1875, p. 15, pi. 1, f. 8-13, 
especially Figs. 10, 11, 13), but these differ in the necks not being con- 
