RETORT ON THE OPHIUROIDEA. 30 



),> 



Fig. 5. Gorgonocephalus pourtcdesii, Lym., 1 1 °. Horizontal cross-cut of the end of an 

 ovarial lobe, showing its wall, and the egg clusters, each of which is sur- 

 rounded by a membrane. 



„ 6. Euryaleaspera,Lrak.,%. Vertical cross-cut of the disk, passing near one arm, 



on the right; and about through the centre of an 

 interbrachial space, on the left. Above is the 

 digestive cavity with its radiating membranous 

 partitions, and a much expanded genital opening 

 (no) on each side. Below are the mouth angles, 

 cut through, and teeth (d") ; partial ring canal 

 (<?,/) ; corresponding to the inner perihsemal, and 

 which connects the inner ends of the ovarial pouches ; 

 second mouth tentacle, above which is the first (•/•") ; 

 radial shields cut through (1,1). 



„ 7. „ ,, l£. Vertical section of skin from roof of disk. It seems 



uniform and somewhat fibrous, except the lowest 

 granular layer, which may, and should be the egg or 

 spermatozoon bearing tissue. The upper dark band 

 is the pigment layer. 



„ 8. ,, „ 7 -J°. Some cells from the lowest granular layer of fig. 7, 



after long immersion in alcohol. 



,, 9- ,, ,, 3 f°. Bit of lime network from the wall of an ovarial 



pouch. 



PLATE XLVI. 



(For further observations, sec the description of the genera and species referred to.) 



Fig. 1. Ophiocreas cedipus, Lym., $ , -*-. Base of an arm and outer margin of disk, with 

 the skin slit on one side and folded back, exposing the right, double-lobed 

 spermary (S,S) connected within with a spermatic bursa or pouch, which 

 empties outwardly by a genital opening (no). Above is the digestive cavity 

 (St). 

 ,, 2. Astrocnida isidis, Lym., ?, f. [Exp. U.S. str. " Blake."] Vertical cross-cut 

 passing through a part of the disk, and somewhat on one side of the median 

 line of an arm, showing the less complex Astrophyton character of the 

 internal arrangement ; folds of the digestive cavity (St') which has no points 

 of attachment on its under side ; the ovaries ($) or egg-clusters lying in the 



(ZOOL. CHALL. EXP. — PART XIV. — 1882.) 47 



