158 THE VOYAGE OF H.M.S. CHALLENGER. 



Species of HemiphoUs uot herein descriljed. 



Hemipholis cordifera, Lym. (PI. XL. figs. 8-12 ; PI. XLIV. figs. 13-lG). 



Hemi/plioiis cordifera, Lym., 111. Cat. Mus. Comp. ZooL, No. i. p. 137, pi. i. figs. 1-3, 186-5. 



Asterias cordifera, Boso, Hist. Nat. Vers., vol. ii. p. 138, pi. ii. fig. 3, 1830. 



Opliiura elongata, Say, Journ. Phil. Acad., vol. v. p. 146, 1825. 



OpMolejiis eloiigata, Miill. & Tr., Syst. Ast., p. 95, 1842; Stimp., Proc. Bost. Soc. Nat. Hist., 



vol. iv. p. 225, 1852. 

 OpMolejJis uncinata, Ayres, Proc. Bost. Soc. Nat. Hist., vol. iv. p. 250, 1852. 

 Hemipholis elongata, Agas., MS. 



Amphiura elongata, Ltk., AdJit. ad Hist., part 2, p. 115, 1859. 

 Ampihiura cordifera (Bosc), Ltk., Addit. ad Hist., part 2, p. 120, pi. iii. fig. 2, 1859. 



West Indies. 



IIemi2iholis gracilis, VIL, Trans. Conn. Acad., vol. i., part 2, p. 262, 1867. 



Hemipliolis o/ffinis, Ljn., 0\)\\. Viv. Of. Kong. Akad., 186G. 

 Guayaquil. 



Hemijyholis microdiscus, Duncan, Journ. Linn. Soc, vol. xiv. p. 467, pi. x. figs. 

 20-22, 1879. 



Korean Strait; 51 fathoms. 



JIemi2oholis wallichii, Duncan, Journ. Linn. Soc, vol. xv. p. 138, pi. vi., is a very 

 young animal, with a disk not more than .5 mm. in diameter. It is not possible to dis- 

 tinguish either the genus or the species. 



OpliiopJiragmus. 



Ojihiopliragmus, Lym., lU. Cat. Mus. Comi). Zool., vol. i., 1865. 



Disk small and delicate, furnished with naked radial shields, and fine overlapping 

 scales ; the scales along the edge of the disk are turned up, so as to make a little fence. 

 Teeth. No tooth-papillae. Mouth angles short and small, bearing six close-set little 

 papilla;. Arms slender, even and more or less flattened. Arm-spines short and regular. 

 Two genital ojjenings in each interbrachial space. 



It is in the structure of the mouth frames that this genus, as illustrated in O^^liio- 

 pliragmus wurdemani is peculiar. The upper brachial rims of the contiguous halves 

 form an elevated crescent embracing the outer end of the mouth slit ; while the inter- 

 brachial rims or wings (PL XL. fig. 4, /) rise as steep crests whose free side (fig. 7) 

 has deep radiating grooves for the attachment of the external mouth frame muscle. 

 Similar, Ijut not at all so large, grooves are found in Ophiocoma, but there is nothing in 

 the character of either genus that seems to call for such a strong attachment. In general 

 l)uild the skeleton is more powerful than that of Amphiura. The radial shields are wide 

 and thick ; the genital plates stout and club-headed, while the arm bones are stouter and 



