242 ARTHUR DENDY. 



Family 5. — Amphoriscid^, Dendy (4). 



Diagnosis. — There is a distinct and continuous dermal 

 cortex over the chamber layer. Conspicuous subdermal 

 quadriradiate spicules, with inwardly directed apical rays, are 

 present. The flagellated chambers vary from elongated and 

 radially arranged to spherical and irregularly scattered. 



Remarks.— In this family, which does not by any means 

 correspond to von Lendenfeld's " Amphoriscinse '' (lO)j the 

 distinguishing characteristic is the presence of subdermal 

 quadriradiate spicules with inwardly directed apical rays. 

 These, as I have already pointed out, are not to be regarded 

 as homologous with the subdermal sagittal triradiates of the 

 Heteropidae, although they appear to fulfil the same function. 

 We find in this family exactly the same series of variations in 

 the canal system as in the two preceding, and, as before, I 

 have utilised this variation, so far as the Syconoid and 

 Leuconoid types are concerned, for purposes of generic dis- 

 tinction, including the Sylleibid type in the Leuconoid. 



The family is evidently to be derived from a Grantia-like 

 ancestral type, by the development of conspicuous and inwardly 

 directed apical rays by the triradiates of the dermal cortex. 



Genus 16. — Heteropegma, Polejaeff (8), fig. 20. 



Diagnosis. — The flagellated chambers are elongated and 

 arranged radially around the central gastral cavity. There is 

 a vestigial tubar skeleton of minute radiates. The dermal 

 cortex is very thick, composed principally of triradiate spicules. 



Remarks. — This genus is extremely interesting as showing 

 how the primitive articulate tubar skeleton, which is on the 

 verge of disappearance, is gradually replaced by the development 

 of the subdermal quadriradiates (fig. 20). Polejaeff" (8) makes 

 no mention of the subdermal quadriradiates in his diagnosis of 

 the genus, although he was well aware of their presence, and 

 I have therefore been obliged to draw up a fresh diagnosis. 



The genus was founded for the reception of Heteropegma 

 nodus gordii from off the Bermudas and Cape York, and 



