270 PROCEEDINGS OF THE ACADEMY OF [1887. 



tally, brauching dichotomously and communicating with those per- 

 taining to the neighboring oscular systems. Incurrent apertures nu- 

 merous, circular, about O'l mm. in diameter, though some are much 

 smaller." 



(2) Potamolepis chartaria, Marshall. 



"Oral cone isolated with round, entire margins 0"8-l mm. in diam- 

 eter. Incurrent apertures not numerous, 0*1 mm. in breadth. Sur- 

 face like blotting paper, with a dermal skeleton composed of very 

 delicate, felted, straight acerates 0*08 mm. long. Color of sponge 

 when dry, chocolate-brown." 



(3) Potamolepis pechuelii, Marshall. 



"Sponge crust-like, with numerous oscular cones 10 mm. high, oval 

 at base; the longer and shorter diameters being about as 2 to 1. 

 These cones are placed in rows in the direction of their longest diam- 

 eters and are generally inclined at an angle of about 45. The spic- 

 ules of the species are more slender and less bent than those of either 

 of the others. The color of the sponge is ash-gray with a silky lusr 

 tre, and this and the large size of the meshes give it the appearance of 

 coarsely porous pumice-stone." Marshall, abridged. 



As before remarked, the skeleton spicules tlu'oughout this genus 

 closely resemble those of Uruguaya ; both being stout, cylindrical, 

 curved, with hemispherical terminations. I understand Mr. Mar- 

 shall to say that he would probably have attached his species to 

 Mr. Carter's genus if its title had not been so "inconveniently local." 



The reader is referred to Dr. Marshall's })aper on these Congo 

 sponges, for many interesting and valuable observations. 



(VIIc.) Gen. LUBOMIESKIA ? 

 (1) Lubomirskia baicalensis, Pallas. 



Mr. Carter remarks : "One learns from the figure of this species, 

 that it consisted of long digital processes, about 14 inches long by 

 one half an inch in their greatest diameter ; more or less uniform- 

 ly inflated at short intervals (that is, bullate), but solid throughout. 

 (Dr. Marshall remarks tliat specimens liavc been found 60 centimeters, 

 nearly 24 inches, high.) Structure elastic, but not crumbling be- 

 tween the fingers. Color dark gray or olive green. .Skeleton spic- 

 ule curved, fusiform, gradually sharp pointed, spiniferous generally, 

 but especially towards the ends, while in some cases the rest of the 

 shaft is smooth. Parenchyma spicule a smooth, thin acerate." 



Carter. 



Log. Lake Baikal, Central Asia. 



