BY E. F. KALLMANN. 459 



malformed individuals (occiirriiiif least rarely in T. diyilatn,^) are 

 met with amongst them; and, in T. pit^fuloans, they are in part 

 reduced to spheres: but otherwise they have the form of short 

 straight rods, rounded at the extremities, often centrotylote, 

 always cpiite smooth, and usually relatively stout. 



The canal-system (PL xxiv., fig.3; PI. xxv., fig.2) is of the 

 a})hodal type, with oval to spherical Hagellated chambers, though 

 with extreinely short aphodi. The chambers measure from 25 

 to 35/'. in diameter, and occur closely scattered throughout the 

 entire extra-axial choanosome; witliin the region occupied by the 

 axial skeleton, however, they are absent, except in the youngest 

 portions of the sponge {i.p., towards the extremities of the 

 branches). In conformity with tlie symmetry of the skeleton, 

 the main inhalant canals proceed from the subdermal spaces 

 towards the interior in a radial direction, parallel to that of the 

 radial skeletal fibres, and are traceable inwards almost to the 

 axial fune; at their commencement, they are of such diameter as 

 to be very distinctly visible to the naked eye, when a thin layer 

 is pared from the surface (PI. xxvi., fig.2). The subdermal 

 spaces are inextensive — least so in T. pustidusus. The ecto- 

 somal layer, or dermal membrane, varies in thickness in the 

 diff"erent species, from 50/'. in T. nirporosufi to (occasionally) 

 140/i. in T. fa^tifjatus, and, when best developed, has very much 

 the appearance of a thin coi'tex; it is densely packed with sjiirula? 

 usually throughout, or nearly throughout, its entire thickness. 



In none of the species were ova or embryos observed. 



Trachycladus scabrosus, sp.nov. 

 (PI. xxi., fig.4; PI. xxiii., fig.9; PI. xxviii., fig.6.) 

 Diaipiosis. — Branches cylindrical, rather slender; of approxi- 

 mately unif(jrm diameter throughout their length, Surface densely 

 beset with small, sharp conuli formed by the exti-emities of the 

 radial skeletal fibres. Dermal layer comparatively thin; superfici- 

 ally packed with si)irula^. Oscula and pores ('). Skeleton with an 

 extremely dense axial fune of diameter exceeding the length of the 

 radial fibres. Radial fibres directed nearly perpendicularly to the 

 skeleton-axis, mostly between 120 and 170/a in stoutness, com- 



