NATURAL HISTORY 39 



1856; Fischer, 1864) and of Ireland as described and photographed 

 by Southern (19 15) in the rock pools of Clare Island (see also Forbes, 

 1 84 1, p. 169 for its occurrence in Ireland). P. lividus is not found in 

 holes around Naples nor is any other species, probably because there 

 is little tide there. Psammechinus miliaris has been reported as rock- 

 boring on the French coast (Cailliaud, 1856, and other older investi- 

 gators), but Runnstrom says (personal communication) that it is not 

 rock-boring on the Swedish coast. The California form, Strongylocen- 

 trotus purpuratus is rock-boring (A, Agassiz, 1872- 1874, p. 706; Ricketts 

 and Calvin, 1948, p. 129, and Plate XXVII). It has recently been 

 reported that this form bores into steel piles and has caused damage to 

 the piles driven by oil companies for their oil-well piers near Santa 

 Barbara (Irwin, 1953). Fewkes (1890a, b) has reported that S. droba- 

 chiensis makes excavations in the rocks at Grand Manan in Canada, 

 as well as two species, Eucidaris thouarsii and Echinometra vanbrunti, at 

 Guaymas Harbor in Mexico. According to John (1889), Arbacia lixula 

 in the Azores makes holes in the lava rocks. It is generally agreed that 

 the boring is done with their spines and teeth, aided by waves and 

 currents. As the animals grow, they often become imprisoned in their 

 holes. For reviews of rock-burrowing Echinoids, see John (1889) and 

 Otter (1932); they also discuss the methods of boring. Echinocardium 

 cordatum is an interesting sand-burrowing form (Grasse, 1948, p. 198; 

 Yonge, 1949, p. 238). 



2. - Distribution 



Arbacia punctulata occurs along the North American east coast from 

 the southern coast of Cape Cod to Florida; Woods Hole is probably 

 its northern limit. It also occurs on the north coast of Cuba, in Yucatan, 

 Cura9ao, Trinidad, and Tobago, but not in the Lesser Antilles, Jamaica, 

 Puerto Rico, or Bermuda. (H. L. Clark, 1902, 1923, 1933; Mortensen, 

 1935, M II, p. 575). The species is supposed to have arisen together 

 with the closely related A. spatuligera on the west coast of tropical 

 America and to have reached its present home on the east coast while 

 there was still open water between the Caribbean Sea and the Pacific 

 Ocean; the original species then diverged into the present two species, 

 A. punctulata and A. spatuligera. The origin of the Mediterranean form, 

 A. lixula, cannot be traced. 



Around Woods Hole, many years ago (1874-19 19) Arbacia were 

 taken in many places in Buzzard's Bay and Vineyard Sound, near 

 Quisset, North Falmouth, North of Nashawena, Kettle Cove, off West 

 Chop (Martha's Vineyard), Sankaty Head (Nantucket), and around 



