162 ECHINOIDEA. 
SPATANGID A (see p. 31). 
Key to the Genera of Spatangide. 
A. Peristome nearly central............ 1. NEoLAMPAS, p. 162. 
B. Peristome excentric. 
i. No subanal fasciole .......... 2, SCHIZASTER, p. 168. 
ii. A subanal fasciole. 
a. Some of the tubercles much larger 
Phamsthe ests yy crisis teen tere 3. SPATANGUS, p. 164. 
B. Tubercles subequal. 
i, Test highest behind .......... 4, EcurnocarpiuM, p. 168. 
ii. Test not highest behind ...... 5. Brissopsis, p. 172. 
1. NEOLAMPAS. 
Neolampas, A. Ag. Bull. Mus. C. Z.i. (1869) p. 271; 2d. Rev. Ech. 
(1872) pp. 147 & 840; Wyv. Thoms. Phil. Trans. clxiv. (1874) p. 745 ; 
Duncan, J. Linn, Soc. xxiii, (1889) p. 195. 
Test prolonged posteriorly into a short blunt rostrum, and arching 
nearly uniformly from before backwards. Ambulacra flush with 
the surface of the test, and formed of a uniform double row of 
single pores. Well-developed bourrelets and floscelles. 
1. Neolampas rostellata. 
Neolampas rostellatus, Al. dy. Bull. Mus. C. Z. i, (1869) p. 271. 
Neolampas rostellata, 4. Ag. Rev. Ech. pp. 147 & 340, pl. xvii. 
figs. 1-12; Wyv. Thoms. Phil. Trans. clxiv. (1874) p. 745, pl. xix. 
“The single specimen procured in the ‘ Porcupine’ Expedition, 
which was dredged living in 690 fathoms at the mouth of the 
English Channel, is 20 millims. in length, 16 millims. in extreme 
width across the ambitus, and 7 millims. in height. The outline 
from above is not quite symmetrically oval or pyriform, the shell 
bulging on either side somewhat uregularly towards the posterior 
extremity. In profile, the anterior end of the test is the thinnest ; 
the outline rises to the apex and then sinks gradually to the trun- 
cated posterior rostrum, along the top of which it coincides with a 
slight longitudinal ridge. The oral surface of the test also rises 
slightly from the anterior border to produce the depression in which 
the mouth is placed, and from the mouth it sinks towards the trun- 
cated extremity forming the floor of the rostrum. This truncated 
end is occupied by a deep inversion, deepest above, at the bottom of 
which the anal orifice opens. The periproct is oval, large, and plated. 
with small scales. In one specimen there is no trace of the exserted 
anal tube described by Prof. A. Agassiz as occurring in the specimens 
dredged by Count Pourtales in the Strait of Florida. 
“The ambulacra have all precisely the same character. Those of 
the bivium are apparently in slight depressions. This is, however, 
only an effect produced by the slight projection of the sides of the 
posterior rostrum. The ambulacra are not very easily seen, the 
pores are so minute ; by holding the shell up to the light, however, 
they become sufficiently apparent as rows of simple pores passing 
