HEXACTINELLIDA. 15 



With hypodermal pentactins with short, thick, smooth paratangentials, associated with 

 conules or bundles of pleuralia ; hypodermal pentactins entirely absent from the areas 

 between the conules. 



The new genus resembles Rossella in possessing three kinds of discohexasters 

 including ealycocomes, but differs from it in the character and distribution of the 

 hypodermal pentactins. 



In the absence of the hypodermal pentactins from the interconular areas Aulo- 

 rossella approaches Aulosaccus, in which these spicules are entirely lacking. In 

 Scyphidium longispina Ij. the same spicules are restricted to the upper part of the 

 body, and, in that situation, mostly to the conules ; but Scyphidium is devoid of 

 the ealycocomes, and so also is Vitrollula Ij. Possibly when pleuralial bundles 

 are strongly developed, the autodermal surface is less in need of support by means 

 of a layer of hypodermal pentactins, and these latter become restricted to the conules, 

 and their paratangential rays become shortened till they disappear altogether. 



In Aulorossella levis sp.n. only a very few anchor-like pentactins are present in 

 the bundles of pleuralia prostalia ; but these spicules are very abundant in the 

 pleuralial bundles of A. crassa, the pentactins being here wholly covered by the 

 dermal membrane. Apropos of the origin of the anchor-like pleuralia and basalia, 

 Schulze observes (8, p. 83): "This leads me to suppose that the anchors are to 

 be considered as protruded and enlarged hypodermalia." At first the three species 

 of Aulorossella described below were placed under Aulosaccus. Prof Ijima, in his 

 description of Aulosaccus schulzei Ij., the type of the genus Aulosaccus, expressly 

 states, however (5, 112), that no pentactins enter into the composition of the hypo- 

 dermal skeleton ; and, further, only two kinds of discohexasters occur. 



Apropos of the presence or absence of hypodermal pentactins, it will not, I 

 think, be out of place to make here a slight correction concerning the species 

 of Aulosaccus Ijima (5, p. 252 and p. 107), in which genus Prof. Ijima places 

 three species, viz., A. schulzei Ijima, A. ijimai Schulze, and A. mitsukurii Ijima. 

 If Schulze (7, pp. 30, 100, and 10, p. 176) is right in retaining Calycosaccus for 

 C. ijimai Schulze on account of its markedly pinula-like autodermal and autogastral 

 hexactins with their long obliquely directed spines, then Aulosaccus contains only 

 one species, viz., A. schulzei Ijima ; the species mitsukurii belongs, as will be 

 shown below, to Scyphidium. 



With regard to Scyphidium mitsukurii Ijima, the British Museum possesses the 

 specimen referred to by Prof. Ijima (5, p. 121) as O.C. No. 4399, and stated by 

 him to be specifically identical with the type of Scyphidium (Aulosaccus) mitsukurii. 

 The specimen is badly preserved, and patches of dermal membrane remain only here 

 and there ; but in these patches, and beneath the autodermalia, there are hypodermal 

 pentactins with orthotropal smooth paratangential rays. Prof Ijima himself says 

 (5, p. 109) : "If A. mitsukurii were only provided with pentactinic hypodermalia 

 I should have no hesitation in referring it to Scyphidium." Among the autodermal 



