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



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



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



(/'), above which is the first ; mouth frame cut through (/) ; lower arm canal 



(t) ; an arm bone («''). 



Fig. 3. Ophiura daps (?), Ltk., $ , f . [Exp. U.S. str. "Blake."] Vertical cross-cut 



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



fold of its membrane (Bit') which runs upward over the arm ; genital 



lobes (S) hanging in the bursa; the same cut through (S'); inner perihsemal 



canal (fc ) ; position of the outer and inner genital openings (no, no, with 



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



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



(lb) ; folds of the digestive cavity (St). 



,, 4. Ophiocaniax, sp. nov., ? , 1 1 *. [Exp. U. S. str. " Blake."] Vertical cross-cut 



of the upper portion of an ovarial bursa (Bu) whose wall is plated with 



lime scales. Above is an embryo ($'), 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 (*SY) ; section of head of genital 



plate (0.) 



„ 5. Amphiura incana, Lym., $ , x £. Vertical cross-cut through a portion of the 



disk, cutting off one arm, and passing beside another ; spermatic bursa (<5) ; 



convoluted genital lobes (§,'§',§') ; arm (am) ; Polian vesicle (po) ; an 



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



its (epithelial ?) wall. 



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



arms and one interbrachial space cut away to show the typical Ophiuran 



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



(Sin), many of which are made fast to the radial shields (I). 



,, 7. Ophiacaniha vivipara, Ljn., f-. View 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 

 ($') 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, showing a section of one arm with its 

 brachial space and a portion of an interbrachial 



