178 ART. 7. r. IJTMA : HEXACTINELLTDA, IV. 



to the oscular margin, they measure scarcel}^ 1 mm. in length. 

 The proximal ray (shaft) may he twice as long as the paratan- 

 gentials in one and the same spicule. In size and shape the 

 spicules in question seem to agree approximately with those of 

 S[ dowUngl, l)ut the paratangentials in the present species show 

 a noteworthy feature, perhaps peculiar to the species, in the 

 close-set microtuhercles that give roughness to their surface. The 

 microtuhercles are not rounded as usual l3ut take the form of 

 fine, sliort and sharply pointed microspines (Contrih., III., PI. 

 YL, fig. i;>), somewhat as in Lanuginella pupa and Scyphidium 

 longùpina (this Contrih., PI. L, fig. 7 and PL IL, fig. o). They 

 stand nearly vertically or slightly inclined outwards, giving a 

 fine and densely hirsute, rather than " granular," appearance to 

 the surface beset by them. This appearance is acquired by the 

 paratangentials before the pentactins are protruded as prostalia, 

 apparently as the last step in the development of hypodermal 

 (/. e., prospectively prostal) pentactins. This is clearly indicated 

 by those groups of hypodermal pentactins (Contrib. III., PI. VI,, 

 fig. 12) in which the most superficially situated pentactin-head 

 consists of rough paratangentials while another or others following 

 in deeper levels are smooth and successively more slender rayed. 

 A small numl)er of diactins associate with the paratangentials 

 of hypodermal pentactins in forming the support to the dermal 

 lacework. 



The dermalia (Contrib. III., PI. VL, figs. 14 and 15) are 

 predominantly rough pentactins but intermixed with a goodly 

 number of stauractins. The former frequently, but not always, 

 show a knob-like relic of the atrophied sixth and distal ray. 

 Karely and exceptionally I have encountered hexactins among 



