I02 DISCOVERY REPORTS 



the latter I have one of the type series, namely, one of the two specimens recorded by 

 Koehler (1906, p. 6) from Booth-Wandel Island. 



In the following synopsis to save space I have abbreviated references to Koehler's 

 excellent photographic figures, as follows: VII is pi. 7, Koehler, 191 2; XL and XLI are 

 pi. 40 and 41 , Koehler, 1920. The numerals following any of these refer to the figures on 

 that particular plate. 



The Booth-Wandel specimen has long actinal spines, about the same as in VII, 12, or 

 XL, 5 (left side) but not so long as the extremes included under A^C^ below ; nor as short 

 as those of A-, B^O ; it lies between these two. On the whole, specimens with actinal 

 spines shorter than the subambulacrals (either slightly or decidedly) are more numerous 

 than those having the two sets of spines subequal. 



SYNOPSIS OF VARIATIONS OF ODONTASTER VALIDUS 



A^. Actinal intermediate spines as long as, or nearly as long as, the subambulacral spines. 

 They give the actinal intermediate area a shaggy appearance. The outer plates carry only 

 2 or 3 spines although those near the mouth-plates may have 4-7 (XL, i, 2, 5). 

 B^. Marginal, especially the superomarginal plates, small, spaced, paxilliform, especially 

 in interradial region, but increasing in size on ray, although still spaced and paxilli- 

 form; superomarginal plates of interbrachial region with about 12 (6-15) spines; 

 paxillae small, spaced (VII, i, 3; XL, 6, 7; XLI, 4, 5). 



C^. Abactinal and marginal spines longer; paxillae with longer, slenderer pedicels; 

 with the spinelets they resemble little brushes; rays longer and slenderer (XL, 3). 

 St. 368; forma tenuis Koehler. 

 C^. Rays as in C^ and abactinal and marginal paxillae still well spaced, but with 



shorter spinelets; St. 368, 173, intermediate forms. 

 C*. Rays of moderate length and not especially attenuate distally; abactinal paxillae 

 with lower pedicels (as compared to C^) and shorter spinelets; marginal plates 

 virtually without pedicels, their spinelets radiating (the plates as a consequence 

 appearing less widely spaced) or compressed into a brushlike group by reason of 

 which the marginal paxillae appear to be more distantly spaced. There are often 

 I or 2 small actinal 2- or 3-valved pedicellariae, much shorter than spinelets, 

 near mouth-plates (VII, i, 3, 4; XL, 7). St. 164, 23 specimens; St. 173, et al. 



forma validus. 

 B^. Superomarginal plates larger, broader than long, obviously larger than adjacent 

 abactinal paxillae. The spines (15-25) are usually co-ordinated in 3 or 4 transverse 

 series (as in XL, 7, but with more spines, as contrasted with VII, 3). St. 370, St. 456, 

 St. MS 6, et al. forma validiis. 



A^. Actinal intermediate spines distinctly shorter than the subambulacral spines, which, as a 

 consequence, form a differentiated cheval-de-frise along the border of the ambulacral 

 furrow (VII, 2, 8, 11 ; 12 is intermediate with A'^)\ rays usually as in A^C^, but variable; 

 sometimes as long as in forma tenuis. 



B^. Actinal intermediate spines 1-3 per plate on marginal parts of area and 3-6 near 

 mouth-plates (VII, 2). 



C^. As in A^, B^, C^; paxillae small, well spaced; superomarginals of interbrachium 

 small, paxilliform, with 6-15 spinelets; 1-3 small 2- or 3-valved pedicellariae on 

 actinal plates near mouth-plates (e.g. St. MS 6); 58 specimens St. 140; St. 173; 

 St. 368; St. 370, et al. forma validus. 



