22 PEECT SLADEN TEUST EXPEDITION. 



I have dedicated this species to the distinguished Swiss naturalist who has added so 

 much to our knowledge of the Echinoderms of Mauritius. 



Iconaster gardineri, sp. nov. 



I have placed three specimens of diiferent sizes in this genus, and I may remark of 

 one of them that it is so minute that it does not exhibit the leading characteristic of 

 the genus, which is, in the words of Mr. Sladen, " supero-marginal plates united 

 throughout the length of the ray " ; here, again, is a lesson against giving definite names 

 to small Starfishes. I do not notice in the new species " peculiar valve-like plates " at 

 the margins of the adambulacral, but it is to be observed that they are not regularly 

 present in specimens of /. longimanus, which is the type of the genus ; moreover, I do 

 not think that so inconstant a character should be used as a criterion of generic rank. 

 Reference is, further, made to " the character of the adambulacral armature," but 

 nothing more definite is said on that point. 



There is, I think, no disadvantage in placing this new species in an already recognised 

 genus — for the present at least ; it is, as we all too well know, quite easy to make a new 

 genus, if thought necessary, later on. 



The specific characters appear to be : R about equal to 2 ?• ; body almost flat, marginals 

 large, about 20 in number ; granulation rather coarse, very uniform, madreporite not far 

 from centre of disc. 



None of the specimens are quite complete. 



Saya de Malha, 125 fms. 



Astronyx cooperi, sp. nov. 



In general appearance very much like A. loveni, but the radial shields are entire, not 

 broken, and, in the adult, the outer arm-spine is very much longer and is not hook- 

 shaped. 



These two characters are sufficient to distinguish the Indian Ocean species from the 

 northern circumpolar form. The difference in the arm-spines throws light on the im- 

 portance, more than once insisted on in this paper, of taking care not to diagnose species 

 from immature specimens ; in the two smaller examples now lying before me the spines 

 near the disc are small and inconspicuous, though those further out are longer. In the 

 longest specimen the size of all but the most proximal spines is quite striking, and, I 

 think, satisfies the requirements of any creator of a "new species." 



Saya de Malha, 150 fms. 



EXPLANATION OF PLATE 3. 



Fig. 1. Lysaster lorioli from below, somewhat reduced from nat. size. 



Fig. 2. The same surface slightly magnified, to show the oral armature and the disposition of the 



adambulacral spines. 

 Fig. 3. Lysaster lorioli from above, somewhat reduced from nat. size. 

 Fig. 4. The same surface slightly magnified, to show the loose arrangement of the dorsal ossicles. 



