DIAGNOSES OF THE SPECIES. 297 



octaster, 106-137 !'- dia.; more deeply situated discoctaster, gen- 

 erally 200-2G0 r- dia.; secondary principal in length shorter than, 

 or about equal to, the terminals. Microdiscohexaster, 15-23 /nlia. 



A, alatn Ij. — Ovoid in shape ; thick- walled. (Prostal di- 

 actins present ?). l!)ermalia, almost exclusively pentaetins. Gas- 

 tralia, hexactins ; not forming a continuous lacework over 

 excurrent canalar apertures. Oxyhexaster, 144-190 /^ dia.; 

 generally normal, with 2-4 terminals to each principal ; seldom 

 hemihexactinose. Discoctaster, 136-220 ,"■ dia.; secondary principal 

 about equal to, or longer than, the terminals. INIicrodiscohexaster, 

 30-35 fjt dia. 



Genus STAUROCALYPTUS T.T. 



(Diagnosis on p. ICi'I;. 



S. rœpct'i (F. E. 8ch.). — Cup-like, with short stalk -like 

 base. With peculiar pit-like subdermal cavities whence arise 

 nan-ow incurrent canals. Excurrent canalar apertures, relatively 

 very wide (up to 8 mm. dia.) ; all freely ojien. All sj^icules 

 with remarkably slender rays. Pentactinic hypodermalia, small ; 

 with paratangentials under 2 mm. in length. Principal parenchy- 

 malia under 35 !'■ in thickness. Dermalia, slightly rough pent- 

 aetins ; not infrequently stauractins. Gastralia, similar hexactins. 

 Oxyhexaster, 88-130 // dia.; some hexactinose. Discoctaster, 

 128-180 // dia. Microdiscohexaster, 22-24 /^ or more in dia. 



S. fJotrlhtf/i (L. ]\[, Lambe). — Broadly sacciform, somewhat 

 outbulged on one side and narrowed at base. Canalar apertures 



