Narrative of Bahama Expedition. 45 



still water. These overarching rocks are fairly alive on their 

 under surfaces with peculiarly hideous crabs, Grafsns inacu- 

 latus Catcsby,^ called '• rock crabs " by the natives, but not the 

 rock crabs of our northern shores. These are remarkably 

 flattened forms with conspicuous stripes in regular patterns 

 over the carapace and appendages. The facility with which 

 they run along, clinging to the under surfaces of rocks, is 

 amazing. It is exceedingly difflcult to catch them even with a 

 dip-net, so long as they are out of the water, but we found 

 that by forcing them to drop from the rocks they could be 

 scooped up with comparative ease. 



The handsome gasteropod Livonia fica is found in abund- 

 ance, clinging to the under side of these overarching rocks, and 

 most of the species found on the rocks in the cove at ^%^ 

 Island were also encountered on Little Egg Island. 



Six or eight species of serpent stars were collected here, 

 among which was a remarkably pretty blue OpJiiotlirix, an 

 exquisite object under the lens, with its glassy serrated spines 

 and beautifully colored disk. The genera Aniphinra and 

 Anifhiunia were also represented. Here, too, our students 

 iirst collected that striking but only too common sea-urchin 

 Diadenia scfosiuii, with its exceedingly long and sharp spines, 

 from which many a painful wound was received b}' our col- 

 lectors during the cruise. 



Quite a number of Gorgonida^ were secured, the most con- 

 spicuous being the common sea-fan. Rhipidigoro-ia flahclhtiu. 

 It is hard to see what has prevented authors from separating 

 the red and yellow " varieties " of this gorgonian into two 

 species. The difference in color seems absolutely constant, 

 and there is also a marked difference in size, the purple form 

 being decidedly the larger on the average. A constant differ- 

 ence both in size and color would seem to be sutlicient for spe- 

 cific distinction. It is also a fact worth noting that the two 

 varieties do not usually grow together, but in communities in 

 which one or the other is exclusively found or greatly pre- 

 dominates. 



1 Miss Mary E. Rathl)un, of the Smithsonian Institution, lias very Icindly identi- 

 iied most of the braclivuran crabs mentioned or fisrured in tliis narrative. 



