168 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Echinosoma zealandiae A. Ag. and Cl. 



Phormosoma zealandiae A. Agassiz, 1904. Panam. Deep-Sea Ech., Mem. M. C. Z., 

 XXXI, p. 105 ; PI. LI, figs. 1-4. 



Off New Zealand ; 700 fathoms. 



As the specimen on which this species is based is extremely young (24 



mm. h. d.), it is difficult to differentiate it clearly from the other members of 



the genus. Like Phormosoma rigidum, from the same station, it must await 



further material before having its true status determined beyond doubt. 



Echinosoma panamense Mortens. 



Phormosoma panamense A. Agassiz, 1898. Bull. M. C. Z., XXXII, p. 77. 1904. Panam. 



Deep-Sea Ech., Mem. M. C. Z., XXXI, p. 101 ; figs. 145-US. 

 Echinosoma panamense Mortensen, 1907. "Ingolf" Ech., II, p. 24. 



Off Gulf of Panama; 1823 fathoms. 



Plate 67, figs. 1-3. 



The pedicellarioe of this species are remarkably short and stout and show 

 little diversity of form. 



The tridentate pedicellarise (PL 67, figs. 2, 3) are all of essentially the 

 same structure, but differ considerably in size. Mortensen (" Ingolf " Ech. 

 II, p. 24) says he has not found the large form of tridentate pedicellaria in 

 panamense ; as we have also failed to find this form, it probably does not 

 occur in this species. The form which is common, has very wide valves, 

 rounded or bluntly pointed at the tip, in contact for their whole length ; 

 the necks are longest in the small ones and may be very short in large 

 ones ; the stalk only equals the head in large ones, but is four or five times 

 as long as the head in small ones. The valves range from .35 to 1 mm. in 

 length, and the width is two-thirds of the length or even more. In form 

 the valves are almost exactly like those of the Echinothurid which we have 

 called Sperosoma biseriatum (see PI. 65, fig. 18), but the blade is often wider 

 at the tip, the sides being nearly parallel. 



The triphyllous pedicellaria3 (PI. 67, fig. 1) are common and show little 

 diversity. The stalk is about four times as long as the neck and the latter 

 is equal to, or usually exceeds, the head. The valves are like that shown 

 on Plate 65, fig. 19. 



The calcareous particles in the tube-feet are perforated plates of varying 

 size and form, but in general like those shown on Plate 65, fig. 20. They 

 are commonly larger and more abundant than in hispidum. 



