BULLETIN OF THE UNITED STATES FISH COMMISSION. 391 



postage by mail (4th class) will be but one cent per ounce, which the 

 writer will gladly repay, with any other reasonable expenses. He will 

 acknowledge their receipt, giving the names of known species and full 

 credit to the collectors of all that are novel or interesting. Every gather- 

 ing should be marked with its habitat, the date of collection, and the 

 name and address of the sender. 



A principal motive for the preparation of this circular at the present 

 time is found in the desirability of securing as full a representation as 

 may be, of the American forms at least, in a monograph now in course 

 of preparation ; but contributions will always be very acceptable. 



228 South Third Street, Philadelphia, Pa., June, 1883. 



na. 



EXPLANATION OF CUT. 



The accompanying figures are drawn from nature by the aid of the camera lucida and represent the 

 relative sizes and shapes of like parts of several sponges. The statosphere is magnified about 35 times, 

 the spicules of the skeleton, marked a, 150 times, all other figures 225 times. 



1. C arteritis tenosperma — Section of statosphere. (In the other genera tbese are without tendrils.) 

 b, dermal or flesh spicule ; d, birotulate spicule of outer coat of the statosphere. 



2. Parmula Batesii — a, skeleton spicule ; d, parniuliforni spicule of statosphere. 



3. Spongilla montana — a, skeleton spicule. 



4. Meyenia rluviatilis— a, skeleton spicule ; cf, birotulate statosphere spicule and disk of rotnle. 



5. Tubella IYunsylvanica — a, skeleton spicule; d, iuequibirotulate spicule of statosphere and disk. 



6. Meyenia Leidii — a, skeleton spicule ; d, birotulate statosphere spicule and disk. 



7. TJruguaya corallioides — a, skeleton spicule. 



8. Spongilla lacustroides — b, dermal spicule ; c statosphere spicule. 

 D. Spongilla fragilis, var. minuta — e, statosphere spicule. 



10. Spongilla fragilis. var. calumeti — c, statosphere spicule. 



11. Meyenia crateriforma — d, birotulate statosphere spicule. 



12. Meyenia Everetti — d, birotulate statosphere spicule. 



13. Heteromeyenia ar^yrosperma — c, long;/, short, birotulate statosphere spicule. 



14. Heteromeyenia Kyderi— c, long, J short ; birotulate statosphere spicule. 



