122 



Pfeffer. I (juite agree with de Meijeke herein and can add that neither in the 

 pedicellariæ is any distinguishing character to be found. P. Pöhlii must then be 

 withdrawn as a synonym of P. gratiosa. 



Agassiz finds young specimens so unlike the larger ones that „they would 

 at first glance readily pass for young of Heterocentrotus trigonariiis". I must con- 

 firm de Meijere's statement that this is not the case; my smallest specimen (9 mm.) 

 is so exactly like the larger specimens that I am quite unable to understand how 

 even smaller specimens (Agassiz names 6 mm.) could look so different. Agassiz 

 must probably have mistaken some young Heterocentrotus for Parasalenia.. 



This species evidently occurs in the whole Indo-Pacific region. As yet it 

 was only known from Zanzibar and Madagascar in the Indian Ocean ; I can add, 

 besides the Gulf of Siam, the Red Sea, having seen a specimen therefrom in the Bri- 

 tish Museum. On the other hand having examined the specimen in the British 

 Museum I must state that the P. gratiosa from Zanzibar, named by Bell (Op. cit.), 

 is a lapsus for Stomopneiistes variolaris. 



I may here add a few remarks on Psanimechinus riifiis, verruculatus and 

 Ecliinometra oblonga. 



Psanimechinus rufiis (Bell). This species was described by Bell in his 

 paper „On the Echinoderms of Macclesfield Bank", p. 411 as Salmacis rufa. I have 

 examined the type-specimens in the British Museum and lind the species to be no 

 Salmacis at all, but a Toxopneustid of the genus Psammechimis. Further I must 

 state that the Gymnechinus pumilio described by de Meijere („Siboga "-Echinoidea. 

 p. 90) is the same species, de Meliere having kindly lent me his largest specimen 

 for examination. Perhaps the smaller specimens from the „Siboga" are another 

 species, as de Meijere states that two ocular plates reach the periproct. In the 

 larger specimen the apical system is like that figured by Bell, no ocular plate 

 reaching the periproct and all the genital plates being low, thus differing very much 

 from the genital plates in the Gymnechinus-species with excentric periproct. — To 

 the descriptions given by the two authors I may add a few remarks. — The buccal 

 membrane contains a great number of small irregular plates (PI. V. Fig. 16), both 

 inside and outside the buccal plates, which, as pointed out by de Meijere, are 

 placed very far from the mouth, almost at the edge of the peristome. Several 

 bihamate spicules are also found in the buccal membrane. — De Meijere says that 

 the ophicephalous pedicellariæ do not present characteristic features; I cannot agree 

 with him in this respect. They are of a very characteristic elongate form, narrow 

 in the middle (PI. VII. Fig. 43). The tridenlate pedicellariæ (which were not found 

 in the „Siboga"-specimen) are rather small (c. 08 mm., head); the valves are simple, 

 widened in the outer part, with no meshwork in the bottom. The edge is finely 

 serrate in the outer part, irregularly so in the lower part (PI. VII. Fig. 34). The 

 valves are widely separated, joining only with the outer part. — On the figure given 



