62 U.S. NATIONAL MUSEUM BULLETIN 2 72 



114 (part); 1910, p. 137.— Traxler, 1896b, p. 97.— Kirkpatriclc, 1907, p. 



523.— Annandale, 1907b, p. 387; 1911c, p. 76 (part); 1914, p. 245 (part); 



1918a, p. 210 (part).— Rezvoj, 1926a, p. 108; 1929, p. 158.— Gee, 1931e, 



p. 37; 1932c, p. 41; 1933d, p. 456.— Arndt, 1932c, p. 556.— Schroder, 1935, 



p. 98 (part).— Sasaki, 1936, p. 4.— Penney, 1960, p. 11 (part). 

 Meijenia Potts, 1882a, p. 12; 1887, p. 228 (part) .—Penney, 1954, p. 156; 1956, 



p. 38; 1960, p. 46 (part). 

 Ephydatia Weltner, 1895, p. 114 (part). — Annandale, 1909d, p. 402. — Gee, 



1928, p. 225; 1930e, p. 27; 1930b, p. 170; 1930a, p. 87; 1935, p. 263.— Sasaki, 



1936, p. 12.— Jewell, 1939, p. 11.— Rioja, 1940a, p. 187.— Carvalho, 1942, 



p. 267. 

 Pectispongilla Annandale, 1915a, p. 245 (part). — Gee, 1931e, p. 48 (part); 1932c, 



p. 35 (part).— Arndt, 1936, p. 16 (part) .—Penney, 1960, p. 8 (part). 



Type species. — By present selection Spongilla sceptroides Haswell, 

 1882. 



Definition. — Megascleres moderately stout to slender amphioxea, 

 rarely amphistrongyla; as a rule covered with a variable numbtr of 

 minute to conspicuous spines, only in one species entirely smooth. 



True microscleres absent; in the growmg phases of some species 

 immature gemmoscleres of only slightly aberrant shape often abun- 

 dantly present in dermal membrane and inner symplasm, hitherto 

 recorded as microscleres. 



Gemmoscleres rather slender amphioxea or amphistrongyla, invar- 

 iably strongly spined, ranging from moderately long to very long, 

 and from straight to distinctly curved ; their spines often conspicuously 

 aggregated and larger in the vicinity of the tips of the scleres, forming 

 club- or scepter-like terminal structures, or pseudorotules of a varying 

 degree of perfection. 



Gemmules often abundant in maturing sponges, in perennial forms 

 usually rare or absent; they are large and spherical, usually scattered 

 throughout the sponge; when occasionally grouped together at the 

 base they never form a distinct pavement layer; typically with a 

 strong and thick pneumatic layer consisting of air spaces of small 

 size and slightly irregular outline, and with gemmoscleres embedded 

 in this layer more or less radially; foramen invariably tubular, tube 

 delicate, straight or slightly curved, rarely projecting beyond outer 

 gemmular membrane, surrounded by a conical depression created by 

 the displacement of gemmoscleres around the micropyle. 



Sponges ranging from minute cushions to large flat crusts, with or 

 without occasional delicate and cylindrical branches, rarely massive; 

 often an emerald green color owing to the presence of a specific 

 pigment, rarely associated with zoochlorellae. Consistency moderately 

 firm and usually elastic. 



Widely distributed in tropical and subtropical regions of all 

 continents, rarely ranging into cold-temperate climates of both 

 hemispheres. 



