1887.] NATURAL SCIENCES OF PHILADELPHIA. 223 



length about three times the diameter of the rotules; shafts nearly 

 cylindrical, sometimes more slender near the middle, irregularly 

 spined ; spines long, acute. Rotules flat, deeply notched ; rays ir- 

 regular, acute." 



"^leas. Skeleton spicules 0-0152 by 0*0006 inches. Length of 

 birotulates 0-0021 inches. Diameter of rotules 0.0009 inches." 



It is added that "this species (var.) collected by Prof. E. D. Cope 

 in Lake Xochimilco, about eight miles south of the city of Mexico, 

 differs from the familiar 31. fluvlatilis chiefly in the far greater 

 length of the shafts of the birotulate spicules. The specimens 

 examined were probably collected in an immature condition, as 

 suggested by the abundance of sarcode and the scarcity of gemmulse 

 or statoblasts. The single small group that alone rewarded a care- 

 ful search through the whole mass of material sufficed, however, to 

 fix its generic and approximately its specific relations. The shapes 

 or proportions of the birotulate siDicules would probably indicate its 

 association with the following. 



Meyenia fluviatilis, var. angustibirotulata, Carter. Ann. and Mag. etc., 

 June 18S5, p. 454. 



"Sponge coating the stems of aquatic plants to the extent of one 

 sixth of an inch in thickness all around. Consistence elastic, fragile. 

 Color light yellow-brown. Skeletal spicule smooth, curved, fusiform, 

 gradually sharp-pointed, varying in size under 75 by 3-6000 ths. 

 inches in its greatest dimensions. 



Statoblast globular, even on the surface, and white in color when 

 fully developed ; iufundibularly depressed over the hilous opening 

 of the chitinous coat; aboutg ffp ths. inches in diameter ; consisting of 

 the usual germinal contents, surrounded by a layer of birotules in 

 juxtaposition, arranged perpendicularly over the chitinous coat, 

 and filled in between with a microcell-structure up to the umbos of 

 the birotulates, which, being naked and allowing the light to pass 

 through them, present a dark point respectively, like minute holes 

 in the midst of the white microcell-substance ; birotule consisting 

 of a cylindrical shaft, more or less constricted in the middle, which 

 is sometimes furnished with one or more spines; rotule fringed 

 toward the margin rather than denticulated, so as to present a stri- 

 ated appearance, which does not reach the umbo or centre ; total 

 length of birotule about e offoths. inches." Carter. 



Log. England and America. 



'O 



