24 EDWAK1> T. [{ROWNR. 



on liltcratinu fnnii its Hydroitl, either has ouly lour porradinl tentacles or eight 

 (four perradial aud four iuterradial) tentacles. The tentacles which appear lat<?r 

 develop in pairs and in the order shown by these figures — 4, 3, 2, 1, 2, 3, 4. Some 

 of the specimens have the groups of tentacles quite close together, which gives the 

 appearance of the tentacles being uniforndy distributed round the margin of the 

 umbrella ; but their position is entirely due to the contraction and shrinkage of 

 the jelly, and this is especially noticeable in the specimens preserved in alcohol. The 

 tentacles are solid, and the endodermal core is in direct contact with the endodorni of 

 the circular (;anal. The lower side of the l)a8al portion of the tentacles in each gr<jup 

 is covered with a layer of ectoderm containing ncmatocysts. There is no well-marked, 

 conspicuous compound basal bullj common to each group of tentacles, such as occurs 

 in Mu/yelui or Chiarella. The tentacles in a semi-contracted condition show at their 

 distal ends conspicuous circular bands of ncmatocysts (fig. 3), but these bands seem to 

 disappear when the tentacles are fairly well expanded, and the ncmatocysts become 

 evenly distributed. There is not the slightest trace of ocelli at tlic base oi the 

 tentacles. 



Family CLADUXEMID^E. 



Prof. Haeckel, in 1879, collected together various genera of Anthomcdusaj 

 having either tentacles with branches, or tentacles bearing appendages armed with 

 ncmatocysts, or tentacles provided with stalked cnidophors, and placed them in the 

 family Cladouemidae. The character of the family has remaine<l practically unaltered 

 to the present day, but the genera liave slightly increased in number "and have been 

 revised and re-clas.sified by Mr. R. T. Giinther (1903) and by Dr. Ilartlaub (1907), who 

 adopts ^Ir. Giinther's classification of the genera. 



The Cladouemidae are divided into two sub- families : — 



1. PteronemidjE with unbranched tentacles having filaments witli ncmatocysts, 



or tentacles armed with cnidophors. 

 Genera — Pieronema, Zanclea, UalocluirUi, Mnestra, Ctenaria. 



2. Dendron^midae, with branched tentacles ; one branch temiinating in a 



sucker or adhesive di.sc, the oth'er branch or branches pnnided with 

 batteries of ncmatocysts. 

 Genera — Eleutlieria ( Clavatelhi) Zancleopsift, Cladonema, Dendronema. 



In accordance with the classification at present in vogue for the Anthomedu.sre, 

 the new Antarctic Medu.sa which I have described under the name of Caiahlniut 

 iceldoni on page 13 should have been described as a new genus of the Cladonemida; 

 and not placed in the genus CaUiblenvi of the Tiaridse. Although this ^ledusa has 

 tentacles which bear appendages or filaments armed with a terminal battery of 

 ncmatocysts, I do not consider that it has any connection with the Cladonemida*. 

 The structure of the gonads, the ba.sal bulbs of the tentacles, and the mouth are 



