LAR SABELLARUM. 427 



description, accompanied by a bcautifnl drawing, that I have liere been enabled to sni)plcmcnt 

 in important details Mr. Gosse's account of one of the most singular and distinct of the 

 Hydroida. 



The fact of the radiating canals in the planoblast being six in number constitutes an unusual 

 though by no means unprecedented condition of the gastro-vascular system. The small tubercle 

 which is interposed between every two tentacles on the umbrella-margin, and which Mr. Hincks 

 informs me contains minute bodies like thread-cells, is probably the origin of what in the adult 

 medusa would become an interradial marginal tentacle. Mr. Hincks has further observed that 

 the gonophore is naked, no ectotheca being present at any period of its development, a condition 

 in which it resembles Clavatella and some other hydroids with undeveloped or naked hydrocaulus. 



It is, however, in the trophosome that the most striking characters are to be met with. 

 The singularly unsymmctrical form of the hydranth, with its tentacles reduced to two, and thrown 

 altogether to one side, and the two lip-like lobes with which the mouth is provided, are characters 

 so unique as to necessitate the separation of Lar from all other known hydroid families. So far 

 as I can judge from the description and figure, the mouth is also situated laterally on the 

 hypostome, being, along with its two lips, directed towards the same side as that which carries 

 the tentacles. 



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