EEPORT ON THE OPHIUROIDEA. 363 



plate (c), teeth {d"), under ami plate (/;), 

 first uuder arm plate (//) ; lip, or marginal 

 membrane of the mouth (jh), tentacle scale 

 {q), scale of the second mouth tentacle {q) 

 (the dotted line ends on a retracted 

 tentacle) ; the papillose tentacle (r), second 

 mouth tentacle (•?•"). 

 Fig. 14. Hemipholis cordifera, Lym., about ^'f°. Longitudinal section of a tentacle, 



showing it to be hollow but imper- 

 forate. Professor Clark notes three 

 component membranes, or layers ; 

 and the peculiar (muscular?) spiral 

 semi-partitions, whose function is 

 doubtless to retract the organ. 

 ,, 15. ,, „ about If". Part of a tentacle, showing the 



rounded end and the papill^. 

 ,, 16. ,, ,, An egg taken from the animal in 



January, Professor Clark notes 

 that it has a bluish-grey appear- 

 ance, and is densely filled with 

 minute yolk-granules. 



PLATE XLV. 



(For further observations see the descriptions of the genera and species referred to.) 



Fig. 1. Ophioghjplia hexactis, E. A. Smith, -f-. Vertical cross-cut of a large viviparous $ 

 parallel to and a little beside the axis of one arm, and through the 

 edge of the opposite interbrachial space. Above are seen two young 

 ( Y, Y') with fragments of arms cut off belonging to them, or to others. 

 One is a tip (near Y) showing the terminal tentacle tube. Threads 

 (Sm) from the roof, supporting the digestive empty cavity ; fold of a bursa 

 (S) ; section of the aboral, or marginal canal (lb), to the left of which is 

 the abductor muscle through whose bundles is thrust the tip of the 

 arm of a young, here seen in section ; a portion of the genital scale cut 

 lengthwise {n) ; genital plate (o) ; lower part of the ovarial bursa {S) ; a 

 fold of the digestive cavity pressing into the bursa {St) ; spines attached to 

 slice of a side arm plate (p, p) ; section of part of the inter-mouth frame 

 muscle {f,m) ; water ring [f, h) ; inner j^erihsemal canal {f,c) ; canal of the 

 ring nerve (w), a section of which is below, while above is seen the smaller 



