ECHINOLAMPAS DEPRESSA. 335 



pear-shaped ; the anus is placed near the blunt end, surrounded by a number 

 of small plates arranged concentrically round it, and extending as a narrow 

 band of small, slender, elongated plates between the single rows of large 

 plates, extending on each side along the other extremity of the anal system. 

 This row of plates consists of five large plates, diminishing in size from 

 the centre of the row towards either extremity ; they carry a few large tuber- 

 cles bearing spines. In the West India species, on the contrary, the anal 

 system is more pointedly elliptical (Pi. XIV. f. 5), the anus being placed 

 almost in the centre, surrounded by a smaller number of small plates radi- 

 ating from it irregularly. The single outer rows are made up of four plates, 

 leaving a triangular space covered by small plates between them and the anus. 

 The rest of the anal system is covered by much larger polygonal plates than 

 in the Pacific species. The buccal membrane is covered by small quadran- 

 gular plates, entirely free from spines, arranged in rows radiating from the 

 mouth, diminishing in size towards the opening of the mouth placed in the 

 centre of the membrane. The absence of teeth is fully confirmed by an 

 examination of this specimen. 



Littoral. 



NUCLEOLIDAE. 



Subfamily Nucleolidae Agass., 1847. C. R. Ann. Sc. Nat, VII. p. 147. 



ECHINOLAMPAS. 



Echinolampas Gray, 1825. Ann. Phil. 



Echini more or less ovoid, apical system eccentric. Ambulacra! petals 

 elongate, unequal, the pores of the same petals frequently differently de- 

 veloped. Actinal surface slightly concave. Actinostome transverse, ellip- 

 tical or pentagonal, more or less eccentric. Floscelle tolerably well marked. 

 Bourrelets moderately prominent. Anal system infra-marginal, transverse. 

 Tubercles of very uniform size ; difference in size scarcely perceptible be- 

 tween the actinal surface and the rest of the test. 



Echinolampas depressa 



! Echinolampas depressus Gray, 1851. Ann. Mag. N. H. 



PL XVI. 



In the first dredging expedition of M. Pourtales, he brought home frag- 

 ments of the ambulacral rosette of an Echinolampas, which must, to judge 

 from the size of the fragments, have attained a length of about two inches. 



