FAORINA. 607 



(LINTHIA.) Faorina. 



Faorina Gray, 1851, Ann. Mag. X. H. 



This genus is at first glance most strikingly similar to Micraster. The 

 lateral ambulacra are scarcely petaloid, slightly sunken, the groove extend- 

 ing to the ambitus, and even beyond ; anterior ambulacra] furrow slight. 

 Peripetalous fasciole often dividing into two anterior circumscribed areas ; 

 short anal fasciole. Actinal surface convex. Median vertical ambulacra! and 

 interambulacral sutures bare. Apical system anterior ; vertex central. 



Faorina chinensis 



! Faorina chinensis Gray, 1851, Ann. Mag. N. H., VII. p. 132. 



PI. XIX". f. 4-6. 



Nearly simultaneous with Gray's description of this species, the affinities 

 of Tripylus were made the subject of an interesting paper by Troschel, 

 to which I referred when speaking of the distinction of several genera 

 established among the Brissina. 



The outline from above is broadly heart-shaped, truncated at the posterior 

 extremity. The longitudinal diameter is but slightly longer than the trans- 

 verse. The test is high, somewhat conical ; the vertex is central, placed 

 immediately behind the apical system. The ambulacral petals are deeply 

 sunken within the peripetalous fasciole ; the depression of the lateral ambu- 

 lacra is continued to the ambitus as a gradually diminishing groove, made 

 somewhat prominent, owing to the great height of the outer edges of the 

 ambulacral and interambulacral plates, and the fact that the vertical sutures 

 of the plates of the median ambulacrum and interambulacrum are left bare. 

 The anterior groove is well marked, and extends to the actinostome. The 

 pores of the anterior ambulacrum are reduced to diminutive pores placed 

 close together, near the apical system, gradually becoming more distant 

 towards the ambitus, where the ambulacral plates are greatly elongated. 

 The lateral petals are straight ; poriferous zones indistinct at first, but after 

 the fourth or fifth pair of pores the poriferous zone is broad, well defined ; 

 the two zones running nearly parallel ; the pores are distinct, not conjugate, 

 terminating abruptly and widely open at the peripetalous fasciole. The 

 poriferous zones are broader than the median interporiferous space. The 



