RECENT OPHIURANS. 183 



radial shield bears a close-set, median, longitudinal series of 7-9 rounded, 

 white tubercles, somewhat larger than the largest smooth tubercles on the 

 arm. On each side of each radial shield is an irregular series of 4-5 smaller, white 

 tubercles. Between the proximal ends of each pair of radial shields, is a single 

 large, white tubercle. In color (specimens dried from alcohol), all the upper 

 surface of disk and arms, except the annulations of hooklets and tubercles, and 

 the tubercles of the disk, which are white, is brown; the lower surface is yellowish 

 white. 



HoLOTYPE (M. C. Z. 2808) and 2 paratypes, (M. C. Z. 2809, 2810). 

 Off Barbados, 56-125 fms. 



These specimens were collected by the Blake and were identified by Mr. 

 Lyman as doubtfully annulata. On the back of one label he has written: " Does 

 Astrocnida sometimes not fork?" The smallest specimen is 4 mm. across 

 the disk and is similar to the larger ones, but the tubercles on the disk at the 

 inner end of the radial shields are larger and relatively much more conspicuous. 

 Study of a series of annulata shows that the two individuals upon which Ltitken 

 somewhat doubtfully based a second species of Asteroporpa (named affinis) 

 were merely variants and that intermediate forms between them and typical 

 annulata are not rare. But no individuals have been seen which are in any way 

 intermediate between annulata and pulchra. 



Species of Asteroporpa not represented in the M. C. Z. 



125. A. AUSTRALIENSIS H. L. Clark, 1909. Mem. Austr. mus., 4, p. 547, pi. 54, f. 

 Wales: off Wollongong, 5.5-56 fms. 



Astrocnida. 



Lyman, 1872. Ann. sci. nat., ser. 5, 16, no. 4, p. 1. 

 Type-species: Trichaster isidis Duchassaing, 1850. Anim. Rad. Antilles, p. 6. Monotypic. 



126. A. ISIDIS (Duchassaing). 



Trichaster isidis Duchassaing, 1850. Anini. Rad. Antilles, p. 6. 



Astrocnida isidis Lyman, 1872. Ann. sci. nat., ser. 5, 16, no. 4, p. 1. A. Agassiz, 1888. Bull. 

 M.C. Z., 16, p. 11.5, f. 400. 



4 specimens. Off Montserrat, 88 fms. Off Barbados, 56-100 fms. 



