HIPPOTHOA DIVARICATA. 289 



than high, with a boss in front, borne on cells of the 



normal size. 

 Var. /8 (carinata, Norman). Zocscia and connecting fibre 



traversed by a prominent ridge-like keel. 

 Var. y (Patagonica, Busk). Zocecia oval, more or less 



attenuated downwards, irregularly annulated, thick. 



HABITAT. On shells (chiefly), stones, &c., from between 

 tide-marks to deep water. 



LOCALITIES. Generally distributed. Special localities 

 must be accepted with caution, as this form has been 

 hitherto confounded with H. flagellum. Var. /3. Antrim 

 (Hyndman) : Birterbuy Bay (A. M. N.). Var. a. Sid- 

 mouth, on red weed (T. H.). Var. 7. ? Britain (Busk). 



GEOGRAPHICAL DISTRIBUTION. Mediterranean (Lamx.) : 

 Roscoff, rare (Joliet) : France, S.W. (Fischer) : Bergen 

 (A. M. N.) : Arctic seas to Spitzbergen, on Ascidians, 

 Astarte, Saxicava, in great depths (Smitt) : Godhavn 

 Harbour, Disco, 5-20 fathoms ('Valorous ' Exped.) : Gulf 

 of St. Lawrence (Dawson) : Mazatlan, on Murex; Hob- 

 son's Bay, Australia (T. H.). Var. Patagonica : Pata- 

 gonia and Falkland Islands, on Fucus (Darwin) : Tasmania 

 (Busk). 



RANGE IN TIME. Pliocene, Castrocaro, very rare (Man- 

 zoni) : Scotch Glacial deposits (Geikie) : Palaeolithic (A. 

 Bell). Var. Patagonica : Coralline Crag (S. W.) : Hip- 

 purite limestone, St. Grlgoire, near Rennes (Michelin). 



Of the varieties of this common species with which I am 

 acquainted, the most remarkable is the one described as 

 var. a (conferta). In this form the zorecia are generally 

 massed together and laid side by side, and do not assume 

 the ordinary dendritic mode of growth. Occasionally 

 lines of cells arranged in single series are given off from 

 the mass. The connecting fibre is very slightly developed ; 



u 



