INVERTEBEATA, CRYPTOGAMIA, MICROSCOPY, ETC. 959 



not small group of naturalists who have not under their hands so 

 large a series of forms as is fortunately to be found in our own 

 national collection. Differences in proportion will not now form the 

 chief ground on wliich new species are established ; and the value of 

 the British Museum series will be hereby extended to those naturalists 

 who, for want of such, are naturally enough led to regard their single 

 immature specimen as the rejiresentative of a new species." 



In dealing with the genus Ambh/jmeustes Professor Bell points out 

 that, in the case of A. griseus and A. formosus, it is possible to detect 

 two very distinct series for each species ; taking the former, we find 

 that there is one series with a small actinostome, a small abactinal 

 area, and a rather wide poriferous zone ; the other has the actinal and 

 abactinal areas very much larger, and the poriferous zone somewhat 

 narrower ; these characters are shown by the table of measurements ; 

 with them, however, there are associated two others, " those with the 

 small actinostome have much larger genital pores and the madreporic 

 plate is much more prominent," In dealing with A. formosus the 

 author enters into greater details as to the sizes of the genital pores, 

 and illustrates his results by showing, by the aid of four entomological 

 pins, of various calibres, how these small orifices may vary in size. 

 He propoimds the possibility of the two series being, in each case, 

 diifcrent sex-form.s of the species, and looks to those naturalists who 

 can get fresh specimens, for a definite resolution of the question. In 

 dealing with Salmacis globator he points out that two very distinct 

 forms appear to have had this name given to them, but he refrains 

 from naming at the present either one or the other, and contents 

 himself with giving a descrii^tion of the two, and figures of them both. 

 He hopes that Professor Alex. Agassiz will be able to set this matter 

 right, as he and his father arc the only two naturalists who have given 

 original descriptions of the sjiecies. 



With regard to changes during growth, one or two examples will 

 show how marked this may be ; if we take Temnopleurus UardwicJcii we 

 find that a specimen 7 mm. in diameter has an anal area 14 '28 per 

 cent, wide and an actinostome 42*8 per cent, wide, while one 43 mm. 

 in diameter has the same parts 9 "02 per cent, and 26 "7 wide ; while 

 Salmacis sulcata has, with 14 mm. for diameter, an actinostome of a 

 width 42 '8 per cent., and when the diameter is 59 mm. the percentage 

 value of the widtli of the actinostome is only 26 • 6. 



Abnormal Echinids.* — Professor Jeffrey Bell and Mr. Charles 

 Stewart direct attention to two cases of abnormalities in these forms ; 

 tliey arc both exhibited by spoi imens belonging to the Teranopleurid 

 genus Amhlypneustcs, and are, wlien taken together, interesting as 

 pointing in opposite directions ; so far that is, that one describes a 

 quadriradiate and the other a sexradiatc variation from the ordinary 

 pciitanurons arrangement. 



Mr. Stewart's specimen, wliich was from his own cabinet, and 

 belonged to A. griseus, is remarkable for having "a crost-liko elevation 

 of what ai>pears to be ono of the ambulacra " ; this crest is shown to 



* ' Jnnrn. Linn. Soc' (Zool.), xv. (18S0) pp. 12fi-9. (1 plate.) 



3 S 2 



