464 Prof. P. M. Duncan and Mr. W. P. Sladen on 



quence of their side arra-plates not meeting. This feature at 

 the basal portion of the arm has been noted by Dr. Liitken as 

 occurring in large specimens from Greenland, whilst he re- 

 marks at the same time that in none of the Danish examples 

 examined by him do the under arm-plates touch. 



The largest specimen was taken by Capt. Feilden in 

 Franklin-Pierce Bay, the diameter of the disk (dried) being 

 10 millims. 



Ophioglypha Stuwitzvi (Liitken), Lyman. 



Ophiura Sttiwitzii, Liitken, Vidensk. Meddel. 1857, p. 51, et Add. ad 



Hist. Oph. p. 49. 

 Ophioglypha Stuwitzii, Lyman, III. Cat. M. C. Z. Harvard, i. p. 51. 



Two specimens were collected by Capt. Feilden in a dredg- 

 ing made in lat. 65° N., twenty-six miles from the Greenland 

 coast, depth 30 fms. 



OpMocten sericeum (Forbes), Ljungman. 



Ophiura sericea, Forbes, SutHerland's Journ. &c. vol. ii. Append. 



p. ccxv. 

 ? O. alyssicola, Forbes, Linn. Trans, vol. xix. p. 146. 

 Ophiocten Kroyeri, Liitken, Vidensk. Meddel. 1854, et Add. ad Hist. 



Opliiuridarum, p. 52 ; Lyman, 111. Cat. M. C. Zool. i. p. 5.3. 

 O. sericetmi, Ljungman, CEfv. K. Vet.-Akad. Fork. 1864, p. 360; 1866, 



p. 307. 



Coll. Feilden : Discovery Bay, 25 fms., hard bottom ,• Cape 

 Fraser, 80 fms. ; Hayes Point, 35 fms., bottom-temperature 

 29°-5. 



Coll. Hart : Discovery Bay, 15-20 fms., muddy bottom, 

 also at 11 fms. ; Franklin-Pierce Bay, 13-15 fms. 



Disk very flat, with margin forming a sharp angle ; covered 

 with imbricating scales and a superficial squamo-granular 

 layer, through which only portions of the radial shields and 

 primary plates are visible. No disk-incisions, the disk form- 

 ing a little arch over the base of the arms. A row of papillae 

 edges the genital slit, and passes over the arm along the disk- 

 margin continuous with the series from the other side. The 

 first three, or sometimes four, upper arm-plates at the base 

 bear papillge. Side arm -plates meet below, but not above. 

 One tentacle-scale. Three arm-spines, arranged along the 

 outer edge of the side arm-plate, the two upper spines being 

 much the largest. 



The main variation which we have noted in the arctic 

 specimens of this species consists in the greater length of the 

 arm-spines as compared with those of more southern examples. 

 In a specimen 9'2 millims. in disk-diameter the length of the 



