80 CCELENTEEATA 



up to 30 cm. ; with finger-like branches 4 to 10 mm. long : North Carolina 

 to Maine and northerly in 1 to 8 fathoms; very common in Long Island 

 Sound; Europe. 



FAMILY 4. CLIONIDAE. 



Sponges which bore in shells or limestone by some process not 

 understood; monaxial spicules of various forms: 4 genera. 



CLIONA Grant. The sponge begins its existence by boring in the 

 dead or living shells of various mollusks; it honeycombs the shell, arid 

 after having destroyed it, grows over it, forming a mass often 15 or 20 

 cm. in diameter, on the surface of which are small elevations. 



0. celata Grant. Sulphur sponge. Color bright yellow: very com- 

 mon from South Carolina to Maine in 1 to 12 fathoms; cosmopolitan. 



SUBORDER 2. HALICHONDRINA. 



Body not compact but usually fibrous, without a cortex; spongin 

 usually well developed: 13 families. 



FAMILY 1. SPONGILLIDAE. * 



Fresh-water sponges. Body variable in shape and forming an irreg- 

 ular mass incrusted on stones, sticks, plants, etc., up to the size of the 

 hand, or larger, and yellow or brown in color, or green where exposed to 

 the sunlight, as the result of the presence of zoochlorellae ; spicules of 

 two principal kinds, (1) the megascleres, slightly curved needles or rods 

 occurring in the mass of the sponge and (2) the microscleres, much 

 smaller needles, rods or amphidiscs (two star-like plates joined by a rod) 

 (Fig. 139, B) which occur in the sponge or form the shell of the gem- 

 mules; asexual reproduction by gemmules, these being globose buds 

 about .5 mm. in diameter, which may occur throughout the sponge, being 

 present mostly in the latter part of the summer and in the fall: about 

 10 genera and 50 species, of which 21 occur in this country; in fresh and 

 sometimes brackish water, both in running streams and in ponds and 

 lakes, from the surface to a depth of 200 feet; cosmopolitan. 



Key to the American genera of Spongillidae: 



! Gemmules without tendrils or projections. 



&! No amphidiscs present 1. SPONGILLA 



6 2 Amphidiscs present. 

 Cj Discs of amphidiscs of same size. 



d^ But one type of amphidiscs 2. EPHYDATIA 



d 2 Two types of amphidiscs 3. HETEROMEYENIA 



c. Discs of unequal size 4. TUBELLA 



a, Gemmules with tendrils or projections 5. CABTERIUS 



* See "A Monograph of the Fresh Water Sponges," by E. Potts, Proc. Acad. Nat. 

 Sci., Phila., for 1887. "Spongillidae," by W. Weltner. Siissw. F. Deutschl., Heft 

 11), 1909. 



