Plate 79 



All figures Pycnopodia helianthoides 



G. 1. Marginal and abactina] plates 'if a small specimen from Monterey Bay, enlarged, seen from 

 side. A, abaetinal; S, S, S, spiniferous superomarginals; /, inferomarginals; AD, 

 actinal surface of four adambulacral plates projected upon lateral view to show relative 

 size; base of ray to right. 1«, Abaetinal skeleton made up of small obsolescent plates 

 seen from coeTomic side of radial area near periphery of disk, X3. The two lines of 

 arrows indicate the position of two membranous interbrachial septa which would lie at 

 right angles to plane of drawing. The inner free vertical edge of these septa is at the 

 two uppermost arrows, anil the plates within the elliptical area enclosed by dotted lines 

 fortify the upper part of the septum rather than the dorsal wall. Solid black plates 

 are spiniferous. 



2. Mouth plate and three adambulacrals seen from side X5; Unalaska. a, a, actinostomial 



spines of the farther, hidden mouth plate; the nearer plate having only one, a 1 ; /', 

 suboral spine of the farther plate 



3. Actinal view of two pairs of mouth plates and part of adjacent adoral carina, X3; A, am- 



bulacra! plates; AD, adambulacrals; M, mouth plates. 

 i. Dorsal or coelomic view of a portion of a cleaned actinostomial ring including three radii, 



X5. .4, ambulacral plates; M, mouth plates; 0, odontophore. 

 5. Actinal view of two inferomarginal and eight adambulacral plates of a partly dried alcoholic 



specimen from Xanaimo, British Columbia, X5. 



240 



