488 " THETIS " SCIENTIFIC RESULTS. 



AMPHILEOTUS, Vosmaer. 



AMPHILECTUS MUNITUS, sp. nov. 



(Plate xlvi., fig. 40.) 



Station 36. 



This form is commensal, living in close association with, and 

 completely investing a gorgonoid colony of the family Cornu- 

 laridse — probaVilj a species of &ympodium (?). The spicules are 

 similar to those of S. verrilli, as figured by Wright and Stnder*. 

 The. skeletal portion consists of a hollovi' cylindrical tube of closely 

 packed spicules. The main stem gives off several lateral branches 

 which are disposed in a plane. These develop lateral polyp bads 

 which form low dome-shaped elevations along the branches. Each 

 elevation has a small circular aperture at the summit. These 

 apertures, although oscula-like, are really the openings through 

 which the polyps become expanded. 



The example is 120 mm. in height, and the branches vary from 

 35 to 75 mm. in length and from 5 to 10 mm. in diameter. The 

 sponge forms an even coating over the whole of the gorgonoid, and 

 is about I mm. in thickness. The surface generally is like that 

 of some species of Suherites, and is marked by a very fine reticu- 

 lation, and innumerable minute pores. There is no evident 

 epidermis — at least it is not revealed even with a hand lens — and 

 I failed to find any oscula unless the polyp apertures be regarded 

 as such. Texture slightly resilient but rather brittle. Colour 

 bluish-grey. 



The skeleton consists of stoutish bundles of stylote spicules, 

 without evident spongin. The primary fibres are parallel to 

 the axis of the gorgonoid for a short distance, they then curve 

 outwards and give off several branches, each of which terminates 

 at the surface in a densely packed tuft of radiating spicules ; if 

 transversely arranged binding spicules are disposed ; in the apical 

 portions of the tufts they are few and far between, and obscured 

 by numerous fragments of foreign spicules. 



The primary fibres are about 015 to 2 mm. in diameter, and 

 from 3 to 4 mm. apart ; the secondaries at their origin measure 

 0"1 mm., but as they near the surface they become much wider 

 owing to the spreading out of the spicules; the radiating tufts 

 at the extremities are usually 025 or 0'3 mm. in diameter. 



Megascleres : — straight cylindr cal styli of the fibres and the 

 dermal tufts, with well rounded base and obtusely pointed apex ; 

 size 0-2 to 0-22 by 0-008 to O-Ol mm. 



Microscleres : — strongly bpnt toxa, with short straight ends 

 which are obtuse and apparently smooth ; size 0*04 to 0-05 mm. 

 in length ; these are fairly abundant in the choanosorae. 



* Wright and Studer— Chall. Rep., Zool., xxxi., 1889, pi. xlii,, fig. 12. 



