286 REVISION OF THE MONAXONID SPONGES, i., 



length and up to 3 /x or slightly more in stoutness. In their 

 earliest developmental stages, they have the form of very slender 

 centrotylote amphioxea. 

 Loc. — Port Jackson. 



Familia SOLLASELLID^. 



From the description given below, it will be seen that Solla- 

 sella di'jitata^ the single species on which this family was founded, 

 is unquestionably aberrant, and that it cannot with any justifica- 

 tion be retained in the Axinellidce^ to which it is generally re- 

 garded as belonging. Nor can it be referred to any other of the 

 recognised families as ordinarily defined. In some features, 

 however, it shows a striking similarity to certain Donatiidce. 

 Thus its cortex appears to be exactly similar in character to that 

 of the genera Donatia and Xenospongia] it further resembles 

 Xenospongia and some species of Donatia in having inhalant 

 pore-like apertures localised along lines; and, although not pos- 

 sessed of a typically radiate skeleton — being of ramose habit — is 

 provided, externally to the core-region, with a system of fibres 

 which run perpendicularly to the surface, and expand penicill- 

 ately in the cortex. Accordingly, for the reception of the genus 

 Sollasella, either the family Sollasellidc^. wall have to be retained, 

 or the DonatiidcE defined in a broader sense; and of the two 

 alternatives, I think the latter has most to recommend it. It is 

 to be noted that, in Donatia itself, the skeleton is not completely 

 radiate, since there is present a central core-region in which the 

 spicules have a confused arrangement, and, besides this, the 

 spicules Iving between the radial fibres are not always radially 

 directed. 



Topsent(47) has referred, to the genus Sollasella, the species 

 originally described by him as Trachya hystrix. As it now 

 becomes evident that this is a markedly different type of sponge 

 from S. digitata, I venture to propose for its reception a new 

 genus, Pseudotrachya^ to be placed provisionally in the Axinellido'. 



Sollasella Lendenfeld. 

 Donatiid?e(?), typically of ramose habit, with well-dev^eloped 

 fibrous cortex and wdth linearly disposed inhalant openings leading 



