Ortmann — Invertebrate Fossils from Patagonia. 369 

 Diagnoses of new species from the Patagonian formation. 



ECHINODERMATA. 



1. Cidaris antarctica sp. nov. Plates with a moderately 

 large, perforated central tubercle, the neck of which is slightly 

 crenulated. Scrobicule large, surrounded by a circle of small 

 tubercles, between which there are still smaller ones. Spines 

 subcylindrical, often slightly compressed, neck somewhat con- 

 stricted. Articular surface finely striated, with a deep articu- 

 lar groove. Surface of spines closely covered with fine, 

 rounded granules, forming irregular longitudinal rows. 



Only isolated spines and plates, San Julian, Santa Cruz, 

 Upper Rio Chalia, Lake Pueyrredon. 



2. Toxopneustes precursor sp. nov. Test suborbicular. 

 Ambnlacral and interambulacral spaces with 4-8 vertical rows 

 of tubercles of subequal size, those of the ambulacral spaces 

 being somewhat smaller. Poriferous zone moderately broad. 

 Pores in three pairs, the two outer vertical rows separated from 

 the inner row by a small tubercle. All the primary tubercles 

 surrounded by small secondaries and miliaries. Actinostome 

 sunken, and lower surface concave, the actinal cuts compara- 

 tively slight. 



This species differs from the known recent species of Toxop- 

 neustes chiefly in the more crowded tubercles. The most 

 closely allied form seems to be: T.pileolus (Lmck.). 



San Julian ; Shell Gap (Upper Rio Chico). 



3. Cyrtoma posthumum sp. nov. Test subcircular-elliptic, 

 depressed. Apex central, upper side covered with very line 

 tubercles. Ambulacra petaloid, open, lanceolate, subequal, 

 extending about two-thirds from the apex toward the periph- 

 ery, the posterior ones closer together than the others. Anus 

 situated on the upper surface, in a deep depression, of a pyri- 

 form shape, narrow above and suddenly widening toward the 

 periphery. Lower surface of test concave, covered with larger, 

 more widely separated tubercles. Mouth subcentral, sur- 

 rounded by a floscelle. Diameter ca. 110 mm , height ca. 28 mm . 



The peculiar shape of the anal depression brings this species 

 into the genus Cyrtoma of McClelland (Calcutta Journ. Nat. Hist., 

 1840), a synonym of which is Stigmatopygus of d'Orbigny. 

 It is the first Tertiary representative of this so far exclusively 

 Cretaceous genus. 



Lake Pueyrredon. 



Vermes. 



4. Serjmla patagonica sp. nov. Tubes solid, calcareous, 

 cylindrical, irregularly contorted and vermiculatc, growing 



