104 Rev. A. M. Norman on the Genera and 



living gregariously in about 90 fathoms water, forty miles east 

 of the Whalsey Skerries, Shetland. It is, however, apparently 

 extremely local, as, during two summers' dredging on the Shet- 

 land Haaf, it was only met with on this one occasion. 



Antedon Celticus (Barrett). 



1857. Comatula Woodwardii, Barrett, Ann. Nat. Hist. 2nd ser. vol. xix. 



p. 33, pi. 7. fig. 1 (but not C. Woodwardii, E. Forbes, Paleeont, 



Trans. 1852, Radiaria of the Crag). 

 1857. Comatula celtica, Barrett, Ann. Nat. Hist. 2nd ser. vol. xx. p. 44. 



Arms long and tapering, each ray bearing from sixty to seventy 

 pinnae on each side. The two pinnse nearest the disk have each 

 twenty-seven joints; the third, and those above it, eighteen. 

 Each pinna is separated by two joints. The larger filiforni 

 processes (cirrhi) are composed of forty-five joints, gradually 

 tapering, terminated by a claw which is larger than the joint 

 next to it. 



The above is a transcript of the late Mr. Barrett^s description. 

 Two specimens (the only examples as yet known) were dredged 

 by Mr. M'Andrew in the Sound of Skye, in 25-40 fathoms, on 

 a bottom of gravel and mud. This is a very fine Antedon, and 

 very distinct from the other British species. 



Order II. OPHIUROIDEA. 



Body round or slightly pentagonal, depressed, having five or 

 rarely six long arms inserted on, and proceeding from, the oral 

 surface, but not continuous with the disk. Arms very slender 

 and flexible, having a central vertebra-like framework, often 

 encased in scales, and always bearing spines. Reptation by means 

 of the flexible arms and their spines. Mouth inferior, central. 

 Viscera not prolonged into the arms. No special anal opening, 

 the digested matter being rejected through the oral aperture. 

 Respiration effected by means of membranous tentacula issuing 

 from the lower surface of the arms and the ciliated epithelium 

 of the inner surface of the body and arms. No eyes. No pedi- 

 cellarise. No respiratory pores on the aboral surface. Madre- 

 poriform tubercle sometimes present, sometimes absent (in 

 adult) ; when present, situated in one of the interradial spaces 

 on the inferior or oral surface of the disk. Reproductive organs 

 opening by ten apertures (twenty in some exotic genera) on the 

 oral surface near the base of the arms. 



Fam. I. Astrophytonidae. 



Arms generally ramose, but sometimes undivided ; not plated 

 with distinct series of scales. Two radiating rib-like projections 



