130 LAWRENCE M. LAMBE ON 



show a tendency to branch and anastomose and to become diffuse. The styli have their 

 bases embedded in the horny matter of the fibres and are directed outward and upward 

 (Plate IV., fig. 6a) ; separate styli connect the fibres together at irregular intervals. The 

 spicules at the outer terminations of the fibres project considerably beyond the dermal mem- 

 brane. There is no special dermal arrangement of the skeleton Imt numbers of slender styli 

 occur without definite order in the dermal membrane and are also found less abundantly 

 throughout the main mass. 



Spicules. — (a) Megasclera ; of two sizes; (1) Large, stout, slightly bent, sharply pointed, 

 smooth styli, thickest at midlength and with a slightly inflated basal end which is generally 

 smooth but at times shows indications of being spined (Plate IV., fig. 6b) ; varying in size 

 from 0-170 by 0-016 mm. to 0-379 by 0-019 mm. (2) Slender, shari)ly pointed, smooth styli, 

 tliickest at the basal end which is minutely spined and often decidedly infiuted (Plate IV., 

 fig. 6c) ; varying in length from 0-176 to 0-222 mm. and in thickness from 0-006 to 0-0049 

 mm. (b) Micrusdera ; smooth toxa (Plate IV., fig. 6d) varying in size from 0-072 by 0-002 

 mm. to 0-255 by 0-006 mm. ; distributed in considerable numbers throughout the sponge. 



Judging from its spiculation this sponge evidently belongs to the genus Desmacella ; 

 the skeletal arrangement is somewhat plumohalichondroid in its character and at the same 

 time is indefinitely reticulate, the single styli connecting the fibres representing secondary 

 fibres, a combination of characters which in itself is highly interesting. 



Locality. — Sooke, Vancouver Island. 



ESPERELLA SERRATOHAMATA, Carter. 



(Plate IV., figs. 7, 7a— j.) 

 Experia serratohamata, Carter. 1880. Ann. and Mag. Nat. Hist., series 5, vol. vi., p. 19, pi. v., fig. 20a — b 



Sponge (Plate IV., fig. 7) massive, amorphous, consisting of a close aggregation of 

 anastomosing fibres, inclosing rounded or oval meshes which are seldom more than 2 or 3 

 mm. in length. The fibres are generally flattened and expanded laterally where they join 

 each other. Texture firm. Surface moderately even. Dermal membrane thin, spiculous. 

 Oscula small, dispersed, about 1 mm. in diameter. A few sjiecimens of this species were 

 collected by Prof John Macoun in July, 1893, at Sooke, Vancouver Island ; the largest 

 measures about 70 mm. across in all directions. 



Skeleton. — Compact anastomosing fibres about 0-5 mm. in thickness at their thinnest 

 parts and composed of tylostyli, form the main skeleton. The dermal skeleton consists of 

 tylostyli lying without order in the dermal membrane, parallel to the surface. 



Spicules. — (^) Megasclera; of one kind only, viz., straight, rather sharply pointed, 

 smooth tylostyli with basal ends only slightly inflated (Plate IV., fig. 7a;, composing the 

 main and dermal skeletons ; ranging in length from 0-320 to 0-353 mm. with an average 

 thickness of 0-011 mm. (b) Microsclera ; of three khids; (1) Palmate anisochelse (Plate IV., 

 figs. 7i, 7j); averaging in length 0-036 mm. ; not very abundant but found in all parts of the 

 sponge. (2) Very large, simple and contort sigmata (Plate IV., figs. 7b, 7c, 7d) notable for 

 their strongly serrated curved ends ; average length 0-157 mm. ; distributed abundantly 

 through the sponge. Small forms of the sigmata are present which are likewise serrated. 

 (8) Minute, smooth toxa (Plate IV., fig. 7f ) about 0-039 mm. in length ; found throughout 

 the soft parts of the sponge and at the surface. 



