108 ZOOLOGICAL COLLECTIONS MADE DURING [JaU. 4, 



cases, therefore, the descriptions here given may be considered, so 

 far as they go, as revisions of the species in question ; I beUeve 

 that such revisions of many of the current species are urgently 

 needed. 



Order Ceratina, Carter. 



Aplysina(?) regularis, sp. n. (Plate X. 6g. 1.) 



Surface even, set with the slightly projecting ends of the primary 

 skeleton-fibres at intervals of about -5 millim. Vents inconspicuous. 

 Skeleton regular, of primary fibres at right angles to surface, average 

 greatest diameter -057 millim. ; and of secondary fibres, parallel 

 to the surface at regular intervals between the primaries, average 

 greatest diameter about half that of the primaries. Primary fibre 

 pale amber-colour, composed of a raultilaminar horny wall with a 

 thick innermost lamina, enclosing a faintly granular axis closely 

 resembling the wall in nature of substance ; axis about one third the 

 diameter of the fibre. Secondary fibre paler, generally fibrillated to 

 its centre. 



Examined. In spirit and by mounting in balsam. 



External Characters. Form incrusting. Consists of a sheet of sub- 

 stance about 2 mlllims. thick, with a level surface, spreading irregu- 

 larly over about one square English inch of an immense flexible 

 worm-tube. Texture soft, very elastic. Colour (in spirit) pale grey. 

 The surface appears glossy, and is set with a number of minute 

 projecting points, which occur with some regularity at about 

 ^-millim. intervals over it. 



Vents. None apparent. Pores scattered between surface-points, 

 •04 to •! miUim. in diameter. 



Main Skeleton. Composed of a set of primary fibres running out- 

 wards at right angles to surface, and projecting l)y attenuated points 

 to a distance of from -14 to "32 millim. from the surface (they are 

 distant from each other at the surface -35 to 7 millim.), of a 

 secondary set, connecting these, approximately at right angles to 

 them, distant from each other by -18 to -36 millim., and of a tertiary 

 set, running parallel to the primary fibres and connecting the median 

 portions of the secondary fibres. This tertiary set is not always so 

 fully developed as to extend from the base to the surface of the 

 Sponge ; but it is generally represented by a fibre or two in the in- 

 terval between each two primary fibres ; it may possibly prove to be 

 merely the young stage of the primary fibres, from which it differs 

 in its diameter and structure, being about half as broad as an average 

 primary fibre, and having but a thin uni- or bilaminar outer wall, 

 and pale yellow colour, also apparently in not terminating on the 

 surface by a point : it may give rise to a primary fibre. 



Hab. Sandy Point, 7-10 fathoms, on worm-tube. 



Obs. This is probably quite a young specimen ; its habits and 

 size, as compared with those of the other members of the genus 

 Aplysina, seem to show this. The extremely slight difference in 

 appearance between the horny wall of the primary fibre and its 

 granular axis distinguishes it from most, if not all, other Aplysince. 



