276 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



the equator to the Galapagos Islands. Just how it reached the islands 

 cannot be said but judging from the material at hand conditions are not 

 as favorable for it there, as the Peruvian specimens are conspicuously larger 

 and more robust than those from the islands. Of the 82 specimens in the 

 Velero collection, 69 are from the Lobos de Afuera Islands, Peru. They 

 range from 30-68 mm in diameter. The tests are usually brown with the 

 spines a deep bronze-green, their tips more or less reddish, but some indi- 

 viduals are distinctly greenish rather than brown. All are more or less 

 deformed at the abactinal system by the presence of the parasitic crab, 

 Pinnaxoides. Of the remaining 13 specimens, 2 small individuals are from 

 the northernmost station known for Caenocentrotus, the shore of La 

 Plata Isle, Ecuador. They are about 25 mm h. d. and have notably long 

 primary spines. Both are infested with the parasitic crab. Another pair are 

 from Fronton Island, near Callao, Peru, one a mere fragment, the other a 

 good adult, like those from Lobos de Afuera. The other 9 specimens are 

 from the Galapagos Islands, 6 from the reef north of Tagus Cove, Albe- 

 marle Island, one from Tagus Cove, one from Academy Bay, Indefati- 

 gable Island, and one from Sulivan Bay, James Island. They range from 

 24 to 41 mm in diameter, the primary spines are relatively stout, and ap- 

 parently none are infested with the crab, Pinnaxoides. It should be added, 

 however, that other specimens of Caenocentrotus from the Galapagos have 

 shown the presence of the crab. Except for the smaller size and shorter 

 spines, the Galapagos Caenocentrotus is very similar to the Peruvian. 



Distribution. — Guayaquil, Ecuador to northern Chile; Galapagos 

 Islands. 



Type. — Paris Museum. 



Type locality. — Galapagos Islands. 



Depth. — Littoral. 



Specimens examined. — 82 specimens from 8 stations. 



Allocentrotus fragills (Jackson) 

 Plate 44, Fig. 21 



Strongylocentrotus fragilis R. T. Jackson, 1912, p. 128. 



H. L. Clark, 1912, p. 354, pi. 113, figs. 3-6. 

 Allocentrotus fraffilis Mortensen, 1942, p. 232. 



Mortensen, 1943a, pp. 254-255, pi. 30, figs. 10-17. 



If a sea-urchin could ever be called a "beautiful" creature, there is no 



doubt that this species would be a first choice for the title. The delicacy of 



its test and spines is remarkable and the beauty of their coloring is indis- 



