132 



PKOF. G. J. ALLMAK OK" LIMNOCODITTM TICTOEIA. 



The marginal bodies are about 128 in number, and consist of a 

 highly refringent spherical corpuscle surrounded by a delicate trans- 

 parent capsule. This capsule is very remarkable, for, instead of pre- 

 senting the usual spherical form, it is of an elongated piriform shape. 

 Inits larger endislodgedthe spherical refringent body, and it thence 

 becomes attenuated, forming a long, tubular, tail-like extension, 

 which is continued into the velum, in which it runs transversely 

 towards the free margin of this membrane, and there, after becom- 

 ing more or less convoluted, terminates in a blind extremity (fig. 3). 



The reproductive sacs are borne on the radiating canals at a 

 short distance beyond the exit of these from the manubrium. 

 They are of a piriform shape, and spring by their narrow ends from 

 the canal, whence they hang down free into the cavity of the um- 

 brella. Their colour is a brownish yellow, derived from the 

 pigment-cells developed in their endoderm. 



The manubrium is of a similar brownish -yellow colour, due also 

 to the pigment-cells of its endoderm. 



The following notes have been made 

 since the above was received : — 



The attachment of the tentacles is 

 peculiar. Instead of being free con- 

 tinuations of the umbrella-margin, they 

 are given off from the outer surface 

 of the umbrella, at points a little above 

 the margin and at three or four different 

 levels. From these points, how r ever, each 

 may be traced centrifugal ly in the form of 

 a ridge as far as the thickened umbrella- 

 margin (fig. 1). This ridge consists of the 

 proximal portion of the tentacle, which is 

 here adnate to the outer surface of the mT" I 

 umbrella. It holds exactly the position of Diagrammatic meridional 

 the " Mantelspangen," ov peronia, so well SdlTcal^^ througha 

 developed in the whole of the Narcome- u , umbrella; m, thickened 



dusse of Hackel and in some genera of his and pigmented margin ; v, 

 m , t ., T , , . , velum ; I, lithocyst ; r, radial 



Trachomedusae*. Its structure, however, canal; o, circular canal; n, 



differs from that of the true peronia, which nerve-ring; t, tentacles; 

 are rib-like lines of thread-cells marking ' 



* Relations of ' Limnocodium to the Trachomedusae are maintained by Prof. Lan- 

 kester, who refers the medusa to the Trachomedusal family Petasidce. See 'Nature ' 

 for June 17, 1880, and his paper of the same date read at the Royal Society. 



