﻿150 



PROCEEDINGS OF THE 



[April, 1857. 



this species cannot but remind us in appearance of the ocellary 

 body of Bolina among Beroid Medusae. In Chrysomitra, as figured 

 by Gegenbaur, and in this Willsia* they appear to be contained 

 in a tube, which is connected with the marginal canal. When my 

 single specimen of Willsia was dead and contracted, I observed 

 that two of these groups, in some instances, each normally con- 

 taining only three, four or five corpuscles, had been forced to- 

 gether, without destroying the continuity of the membranous wall 

 by which they were surrounded ; a large group had been thus 

 formed, containing nine of these bodies, while the double outline 

 of the membrane by which they were surrounded was still dis- 

 tinguishable. (See pi. 9, fig. 10, b.) As thread-cells they are of 

 a peculiar type, and are much larger than the ordinary thread- 

 cells on the tentacula, and probably have a peculiar function. 



The single specimen obtained of this species was found July 

 4th. Its appearance and carriage in the water is very Thauman- 

 tioid, on account of its numerous tentacula, short digestive cavity 

 and shallow bell. 



ZANCLEA.f Gegenbaur. 



General form nearly that of Sarsia. Exterior of the disk orna- 

 mented with four rows of thread-cells extending from the insertion 

 of each tentaculum a greater or less distance upwards towards the 

 summit of the bell. The thread-cells in the older animals are ar- 

 ranged one by one along the row, but in the younger there is 

 simply a cluster of them above each tentaculum, as represented, 

 PI. 8, Fig. 4,x. Digestive trunk, more like that of Cladonema than of 

 Sarsia, divided at its oral extremity into four short lappets. Sexual 

 organs confined to the upper portion of the digestive trunk. Ra- 

 diate tubes four, unbranched. Tentacula four ocelli wanting; 

 marginal bulb very small; shaft of the tentaculum provided for the 

 greater portion of its length with pediculated appendages, the 

 enlarged utricular heads of which contain each a few cells which 

 appear to be thread-cells. 



Larva? — Probably as in Corynitis the young medusa has at first 

 only two tentacula. 



This genus, I think, is related to Cladonema, as Gegenbaur also 

 believes, yet the tentacula are of a very distinct type. The four 

 short appendages of the mouth, however, and the position of the 

 sexual organs are approximations to that genus. 



* Gosse has figured the same structure in Willsia stellata. 

 -j- See p. 125 note. 



