366 THE VOYAGE OF H.M.S. CHALLENGED. 



main, or body cavity ; mouth sphincter (t/») just outside which is the inner 

 perihsemal canal ; spinous papilkB of the mouth (d) ; second mouth tentacle 

 (;•"), al)0ve which is the first; mouth frame cut through {/) ; lower arm canal 

 (t) ; an arm bone (»''). 

 Fig. 3. Ophiura claps (?), Ltk., $ , \. [Exp. U. S. ^tr. "Blake."] Vertical cross-cut 

 beside an arm showing the whole of a spermatic bursa {Bu), with the 

 fold of its membrane {Bu') which runs upward ()ver the arm ; genital 

 lobes ((5) hanging in the bursa; the same cut througli (cV); inner perihtemal 

 canal (/c) ; position of the outer and inner genital openings {no, no, with 

 arrows) ; parts of side arm plates cut througli (/) ; adductor muscle {rm) 

 between the genital plate (o) and the radial shield (/) ; outer blood ring 

 (Jh) ; folds of the digestive cavity {St). 

 ,, 4. Ophiocamax, sp. nov., $ , \^. [Exp. U. 8. str. " Blake."] Vertical cross-cut 

 of the upper portion of an ovarial Ijursa {Bu) whose wall is plated with 

 lime scales. Above is an embrvo (f5'), cut through and lying in a pocket 

 (ovarial tube ?) whose wall also has minute lime scales. The bursa clings 

 closely to the wall of the digestive cavity {St) ; section of head of genital 

 plate (0.) 

 „ 5. Ampliiura ineana, liym., $ , ^^. Vertical cross-cut through a portion of the 

 disk, cutting oft' one arm, and passing beside another ; spermatic bursa (ci) ; 

 convoluted genital Jolies ('V'^','^') ; arm {((m) ; Polian vesicle {po) ; an 

 arm bone from the outer side [w') ; the wrinkled digestive cavity {St), with 

 its (epithelial ?) wall. 

 ,, G. Oplnopholis aculeata. Gray, f. Disk seen diagonally from below, with two 

 arms and one interbrachial space cut away to show the t^'pical Ophiuran 

 digestive cavity, a bag {St) attached to the disk-roof by slender threads 

 {Shi), many of which are made fast to the radial shields (/). 

 ,, 7. Ophiacantlia vicipam, Lju., f . Vie-w from within of a vertical cross-cut through 



two arms {Am) close to the edge of the disk, 

 showing the marginal portions of the digestive 

 cavity {St, St) almost filled by a thick, wrinkled 

 (epithelial ?) layer. Of the bursae, two {SS) 

 appear as simple folds or cracks, while the third 

 {S') has little lobes, doubtless ovarial tubes, 

 connected with it. 

 ,, 8. „ ,, ? , f . Vertical cross-cut at a right angle to the arm, 



a little inside the edge of the disk seen from 

 within, showino- a section of one arm with its 

 brachial space and a portion of an interbrachial 



