SCHIZASTER FRAGILIS. 



363 



of this as well as of others of our Eastern Coast species, is of course prob- 

 lematical ; yet the differences indicated by McCrady do not indicate as great 

 a range of variation as we find in living species. I have quoted the figures 

 for the sake of calling attention to them. There are, in addition, other ter- 

 tiary species described by Michelin and by Guppy, coming from the Gulf 

 of Mexico and the West India Islands ; but as their material was inaccessi- 

 ble to me, I have not attempted to point out their affinities. 



Littoral and fragments from 115 fathoms. 



Schizaster Agass. 1836. Prod. 



Test thin, elongate ; apex posterior ; great difference between length of 

 anterior and posterior pairs of ambulacra. The anterior ambulacrum 

 placed in a deep, broad groove ; anterior and posterior petals somewhat 

 sunken and diverging ; the anterior are nearly parallel with anterior groove. 

 Genital pores varying in number from two to three. Peripetalous fasciole an- 

 gular, running close to the ambulacral petals, with a narrow lateral fasciole 

 starting from the anterior ambulacra and passing under the anal system, with 

 elongate, triangular swellings. Posterior lip of bilabiate actinostome very 

 prominent, turned back, rising to a rounded beak in front of actinal plastron. 



Schizaster fragilis 



! Brissus fragilis Dub. & Kor. 1844. Skand. Echin. 

 I Schizaster fragilis Agass. 1847. C. R. Ann. Sc. Nat. 



PI XXI. f. ,3. 



Test depressed, vertex and apical system almost coinciding; three genital 

 openings, right anterior obliterated. Compared with S. canaliferus, the 

 odd ambulacral groove is less broken and narrower ; the pores arranged in a 

 most regular line ; the pores of each pair separated by prominent, elongate 

 tubercles, making a beautiful line of beads from the apex to the peripetalous 

 fasciole, the flat space intervening between the poriferous zones being cov- 

 ered by small tubercles and granules of little prominence, except the outer 

 rows near the poriferous zone ; the lateral ambulacra are but slightly sunken, 



