ATHORYBIA. 87 



but in other cases I could distinctly observe that they arose from the pedicle of the polypites. 

 In their perfect state they were similar to those of the Calj/cophorida, except in the structure 

 of the sacculus, which nearly resembles that of Agalma. 



This organ is very long, and is coiled up within a large involucrum. The distal end of 

 the sacculus is prolonged into a conical median lobe, devoid of thread-cells, and two lateral, 

 comparatively short, filaments (fig. 9/). 



The involucrum and the filaments contain many small thread-cells {4m^ inch); those 

 which lie in the thickened wall of the sac are, as usual, elongated, about ^Jh of an 

 inch long, and of a deep-brown colour. Thread-cells of a different kind are disposed obliquely 

 to these and imbedded in the proximal half of the walls of the sacculus; they are from 

 two to eight in number on each side, measure aloth of an inch in length, and have 

 an elongated oval form. 



The lateral branches of the teiitacula are first visible as papillae about ~th of an inch 

 in length, composed of the endoderm and ectoderm, and containing a diverticulum of 

 the somatic cavity. These papillae elongate and become tricuspid at their extremities, small 

 thread-cells at the same time making their appearance in their walls towards the proximal 

 end; next a constriction appears in the middle of the papilla, and one wall becomes 

 much thicker than the other. The lateral processes of the tricuspid distal end now 

 elongate rapidly, the central one remaining comparatively stationary, and the thread-cells 

 acquire their characteristic forms (figs, 9« — 9e). 



The involucrum finally makes its appearance as a process of the ectoderm of the basal 

 division of the organ. Up to this time the sacculus has remained straight; its coiling up only 

 takes place subsequently. 



The I'eproductive organs are scattered irregularly upon independent branched stalks 

 or gonoblastidia (fig. 12), one pedicle (always.^) carrying both androphores and gynophores. 

 Small hydrocysts are also developed on the same pedicle. The androphores are longer and 

 rather thicker than the gynophores. The calyx of the former presents a terminal circular 

 aperture, and the characteristic longitudinal canals, though I am not sure there were four of 

 them. 



In the most advanced androphores the manubrium had a reddish colour, and its apex 

 projected beyond the mouth of the calyx ; it contained nearly fully developed spermatozoa. 

 Each gynophore contained but a single ovum. The calyx exhibited its four regular canals, 

 united, in the fully developed organ, by a circular canal surrounding a terminal aperture. 



The gynophore appeared to contain many large superficial anastomosing canals, an 

 appearance produced, as in the case of Agalma, by the irregular and incomplete separation 

 of the outer surface of the manubrium from the inner surface of the calyx. 



I took this Athorybia in the Indian Ocean in April, 1847; on the East Coast of Australia 



in May, 1848. 



The only complete anatomical description of any Athorybia extant is that given by 

 Kolliker of A. rosacea, which occurred abundantly at Messina, and presented many varieties. 

 The hydrophyllia were attached below the air-vesicle to the short, depressed, conical 

 coenosarcal portion of the hydrosoma, in two or three circles, of which the uppermost was 



