REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 107 



spines increasing in length towards the central portion of the scleres, 

 where they are perpendicular and large and often end in rounded 

 knobs; length range 75-85 n, width range 2-3 /x without spines. 



Gemmoscleres bu-otulates of two distinct length groups, in shape 

 only slightly differing from each other; the longer class few in nmnber, 

 with uTegularly cylindrical shafts, as a rule entirely straight, bearing 

 conspicuous conical spines in a variable arrangement, and terminally 

 with strongly umbonate rotules, bearing at then- margins a number of 

 deeply incised recurved teeth; the smaller class considerably shorter 

 and more abundant, their cylindrical shafts often spined, their 

 rotules similar in shape to those of the longer class; length range of 

 longer class 80-85 fx, of shorter 50-60 n; diameter of rotules in both 

 about 22 fji. 



Gemmules not very abundant in mature sponge, ranging in diameter 

 450-480 fi, shghtly subspherical; pneumatic layer well developed and 

 granular, consisting of minute spherical air spaces; shorter gemmo- 

 scleres contained A^dthin this layer, longer considerably surpassing it; 

 foramen distinctly tubular, porus tube slender and straight, \\'ithout 

 terminal cirri. 



Distribution. — Widely scattered distribution in eastern parts of 

 the North American Continent, ranging from Louisiana to Canada, 

 also some soUtary records from Germany and Poland; the "variety" 

 H. repens spinulosa described from Mexico. 



Color in life. — Recorded as bright green. 



Discussion. — The failure of Bowerbank (1863) to observe the 

 certainly elusive longer class of birotulate gemmoscleres in his Spongilla 

 baileyi caused a great number of subsequent authors to ignore this 

 species as a possible member of the genus Heteromeyenia, and to place 

 it within the genera Meyenia or Epkydatia. Potts (1887), in transferring 

 his Spongilla repens to Heteromeyenia, expressed the opinion that his 

 species could well be found identical \sdth S. haileyi. However, sub- 

 sequent authors did not find it necessary to revise the type of the latter 

 in the British Museum, and thus H. repens became a rather well- 

 known species, while the status of S. haileyi remained uncertain for 

 more than 60 years. 



In his desu'e to find a better taxonomic arrangement for the rather 

 conglomerate group of spongiUids \vith heterogeneous birotulate 

 gemmoscleres, Schroder (1927b) carried out the first revision of the 

 type material of S. haileyi and corrected and augmented Bowerbank's 

 (1863) original description of this species. After estabhshing the 

 presence of two classes of gemmoscleres in the type, Schroder demon- 

 strated the necessity of considering S. haileyi congeneric with H. 

 repens, as well as with a number of formerly known separate species, 

 and suggested that all these represent mere races of the nominal 



