294 MYRIOZOID^:. 



GEOGRAPHICAL DISTRIBUTION. Mediterranean (Man- 

 zoni) : Singapore, on Tubipora musica (T. H.). 



RANGE IN TIME. Pliocene deposits (newer), Calabria; 

 Castrocaro (" Pliocene antico ") (Manzoni) . 



This is a smaller and more delicate species than H. diva- 

 ricata, and may be at once distinguished from it by the 

 shape of the orifice. The cells are rather less produced 

 below than those of the last-named ; they are smooth or 

 slightly wrinkled transversely, and want the keel which, 

 in a more or less pronounced form, is always present in 

 H. divaricata. 



The cell rises a little towards the upper extremity ; and 

 the elongate obovate aperture is therefore prominent and 

 conspicuous. In this respect the species differs markedly 

 from H. divaricata, in which the middle of the cell is ele- 

 vated, and the wall slopes away from the centre towards 

 the upper extremity, so that the mouth is placed slantwise 

 and is less apparent when the cell is viewed in front. 

 The ovicelligerous cells are very small, much smaller as 

 compared with the normal cell than those of H. divaricata 

 the ovicell is regularly globose, smooth and shining, and 

 destitute, I believe, of the kind of boss on the front which 

 occurs in the latter species. 



The fibre is extremely slender, and, though variable, 

 generally much exceeds the cell in length. 



I have met with a very pretty variety (vitred) , in which 

 the cells are exceedingly small, perfectly vitreous and 

 transparent, and very widely separated, the connecting 

 fibre being three or four times the length of the zooecia. 



[HlPPOTHOA CASSITERIDES, Couch. 



HIPPOTHOA CASSITERIDES, Couch, Johnst. Br. Zooph. i. Suppl. 476, woodcut, 

 fig. 87. 



I only know this species by the description in Johnston's 



