wrr.uuini: \ 01 miutii PACIFIC a\i> UXTACENT usn.i;- m-iii.k 09 



In- counted across ray between the superomarginals. The latter as well as the 

 inferomarginals, and actinals are arenate, broad losenge-ehape up incipientiy four- 

 IhIiiiI. ninl imbricate to form transverse as well as longitudinal series, lower and 

 adoral ends outermost 



The intarbraohial septa are stout and strongly calcified, and their interradial 

 dimension is about one-half r. The actinostomial rin it, decidedly narrow, 



si> ilmt the actinostome is small, and the odontophore is not conspicuous as in AtU 

 amwtnsis. The ambulacra] furrow i- rather narron and the ambulacra! plates are 

 not crowded 



The intestinal coecum is of the Irregular tubular form with a oommon saccular 

 portion adjacent t<> the intestine. The hepatic ooeos are very large and extend to 

 the end » » f the ray. The everaible Btomach has large radial diverticula, the central 

 |)oriinii being defined by th<- inner edges uf the interbrachial septa. The -cpta as 

 mentioned above are about one-half r in breadth. The Bides of the ray art- divided 

 iiitu n series of lateral pockets by means of dorsoventral partitions similar tn those 

 of At&eriai ai tnto these the lateral diverticula of the hepatic coecs extend. 



The gonads are attached to the interbrachial septa about midway between the dorsal 

 and ventral surface and about one-fourth i»f r inn ard from the apex of the interbrachial 

 angle. The gonoduol passes outward and downward in the septum, and opens on 

 the ventral surface about one-fourth r from the interbrachial angle, between the 

 two rows of marginal plates, at the end of a low papilla often guarded by a major 

 pedicellaria. The papillae are very close to the interradial line, one on either side 

 for each interbrachium, and are diffioull to find. The gonad is in form spindle- 

 shaped, a little over one-fourth to one-half K in length and consists of numei 

 short lobulated branohes surrounding a central duct. The eggs are Lai 



Variations. As an example of the variations which may occur at one locality. 



in specimens from station 3233, 7.25 fathoms, Bristol Bay, are very informing. K 

 varies from 31 to 93 mm., Beven examples being large. The range of difference 

 in abactinal armature is shown by Plate 37, Figure l. Plate 38, Figures l and 2. 

 The lirst two are from station 8233 ; the last is from the Arctic Ocean, but a specimen 

 from station 3233 is practically the same. Of the m specimens: (a < me is Pl.it- 

 Figure I : [b) two are between this and Plate 38, Figure l ; c five fall in a class with 

 the latter or have slightly more prominent heaps of spines. For instance, in three 



of the live, the central spine i- more accentuated. (d) t >ne is like Plate 38, Figure 2. 



The variation in superomarginal -pines is !t - follow-: (a) Usually three >ung, 



one or two; c four Bpecimens have generally tWO -pines; two specimens one of 



winch l- young have one -pirn- or sometimes two on distal plate roe -pine 



t\ pica! of polythda I. Of inferomarginal spines a has usually two, the other- one 



Specimens from stations 3231 and 3232 exhibit the same class of rariat 

 ranging through the same amount of difference with the exception that there is no 

 example so near polythda as that in <-la— ./ above 



Specimens from stations 3496, 351 7, and No 39984, of! St George Island, 



have very large bivalved straight pedioellariae like those of the typical aphelonota. 



All are from the region of the Pnlulof l-Iand- Inasmuch a- -ome of the specimens 



of polyihela from the same locality -how a similar variation it would be interesting to 



know t he can 



6 



