Nai^rative of Bahama Expedition. 223 



But a single sea-urchin was secured liere. an Aspidodiadcnia, 

 which does not agree very well with either species described 

 by Agassiz. The spines are ver^- long and banded regularl}- 

 with purple and white. The characteristic sheathed pedicel- 

 lari;v are well shown, but differ somewhat from those pre- 

 viously described. So far as I can ascertain, this genus has 

 not hitherto been found at a less depth than ninet\'-five 

 fathoms. 



The comparative meagreness of the collections so far as the 

 higher forms are concerned, was more than atoned for bv the 

 marvelous series of h3-droids from the ridge connecting the 

 two islands. No less than twenty-six species were brought up 

 in the ten hauls of the tangles, of which eighteen are appar- 

 ently new. It will thus be seen that this spot is one of 

 perhaps unprecedented richness in its hydroid fauna. In less 

 than a single day's dredging here, we brought up a greater 

 number of species of this interesting group than rew^arded our 

 ■week's w^ork off Havana, w^here wc secured twentv-one 

 species in sixteen hauls, or on the Pourtales Plateau, where we 

 secured twenty -three species in forty-three hauls. The pro- 

 portion of new. species w'as also far in excess of an3thing found 

 elsewhere. 



The family HvEECiu.ii was represented Iw Ilalcciuin mac- 

 roccp/ialiiiii i\llman, characterized by verv large hvdranths 

 and small hydrotheca', and a new species of Ilalcciiini which is 

 \'ery minute, and was. found on a bit of sea-weed completeh' 

 buried in a growth of alga and other matter adherent to the 

 .sea-weed. It had the curious habit of growth b}- which new 

 h3^drophores sprouted from the old ones just below their 

 margins. The common Ohelia nuir^'/'iiala Allman was found 

 here, and a species of campanularian, for which a new genus 

 may be necessary unless it can be accommodated in the genus 

 CalyccUa of Hincks. Three species of IfchcUa. all apparentlv 

 new, complete the list of campanularians. . 



Among the Sertularid.e are two new species of Scrhdaria, 

 one of which resembles the next genus in the fact that the 

 liN'drotheca' are in pairs and contingent, although the\' are 



