HAWAIIAN AND OTHER PACIFIC ECHINI. 



Collected by the U. S. Fish Commission Steamer " Albatross," Commander 

 Chadncey Thomas, U. S. N., Commanding in 1902, and Lieut. Com- 

 mander L. M. Garrett, U. S. N., Commanding in 1906. 



SALENID^ Agassiz. 

 The Pedicellari^e and Other Structural Characters. 

 Plates 43, figs. 3-6 ; 45, and 46, figs. 1-8. 



Pedicellari^ are usually common in the recent Salenidae, especially 

 abactinally and on the ambulacra. They are of two quite distinct types, 

 each of which occurs in two forms. One type corresponds to the tridentate 

 pedicellariae of other Echini, but may have either three or four valves ; 

 the latter we may call " quadridentate." The other tj'pe corresponds to the 

 ophicephalous pedicellarise of other Echini, but may be either short-stalked 

 with nearly spherical heads and so may be called " globose" pedicellariee, or 

 they may be long-stalked with more elongated heads and so may be called 

 "ovoid" pedicellarice. The stalk (PI. 45, fig. ^-4) in all the pedicellariaj is 

 made up of a dense, nearly solid calcareous network, and is not narrowed or 

 peculiarly modified in any way at the top. 



Although DiJderlein (1906) has described and given some excellent 

 figures of the pedicellariae of Salenocidaris profxmdi, 8. varispina, and Salenia 

 phoinissa, we have felt that it was desirable to include those species in our 

 discussion of the family, and to give some additional figures. 



The tridentate pedicellarifB (Pi. 45, fig. 3) are fairly common in some 

 species but are rare or entirely wanting in others. When present, they occur 

 on the interambulacra, and mostly near the ambitus. The head is about as 

 long as the stalk, and is attached to it by a short neck. The valves (Pis. 

 45, figs. 10, 11, 16, 17 ; 46, fig. 3) are from half to three-fourths of a milli- 

 meter long, and may be either curved or straight. As the diversities of 

 form which they exhibit are fairly constant, they afford useful specific 

 characters. 



