Development of the Marine Sponges. 323 



stmulans, Johnston, Esperia cegagropila, var., Cart., with still a 

 few specimens of Orantia compressa in this condition, and on 

 the 29th of August Halichondria sanguinea, Johnst., H. in- 

 crustans, J., H.panicea, J., and H. plumosa } J., together with 

 many more specimens of the sponges first mentioned ; so 

 that it would appear that the active reproductive state of the 

 siliceous sponges, viz. that in which they are about to throw 

 off their ova in the state of embryos, should be chiefly sought 

 for in the months of July and August, probably including 

 September, — a point which it appears to me desirable to 

 establish for the advantage of others wishing to follow this 

 pursuit, while before entering upon the development of the 

 ovum and embryo into the perfect sponge it also seems advi- 

 sable briefly to premise, for the same purpose, what expe- 

 rience has taught me in this respect, which is as follows, viz.: — 

 that sponges for the most part grow upon the under surfaces 

 of rocks ; that to obtain the greatest variety it is necessary to 

 be present at the " springs," as the tide falls lowest then, 

 provided the wind be blowing " off ' instead of " on " 

 shore ; that we should work down with the last hour's fall of 

 the tide ; and that this work should chiefly consist in breaking 

 off with a heavy crow-bar such ledges of the rocks as bear 

 sponges of different kinds in large quantities, and carrying 

 them up to a pool far above low-water mark, where they can 

 be examined deliberately after the tide begins to rise, since 

 both the fall and the rise of the tide take place so rapidly 

 that there is no time for examining the specimens at the 

 moment. Particular portions may be knocked off with a 

 heavy hammer and cold chisel ; and good specimens, if they 

 cannot be obtained otherwise, must be loosened at the base 

 with a putty-knife or spatula. 



Besides these instruments I carry with me a clasp-knife to 

 cut off the overhanging " sea- weeds " which intercept a view 

 of the rocks beneath, and a little pad or canvas pillow stuffed 

 with air and attached to a leather strap and buckle (which may 

 be gartered round the right leg just above the calf to protect 

 the bare knee against the cutting rock &c, as it is almost 

 always necessary to bend down very low to see the under sur- 

 face), a shrimp-net on a 6-feet pole, and weeding-iron on the 

 like, to cut off and catch specimens which may be hanging 

 from the under surface of the rocks beyond arm-reach, a 

 2-inch focus watchmaker's eye-glass, and two or three tin 

 cans with covers (slung to strings attached to lateral ears, 

 which they should each have for this purpose), to receive the 

 selected specimens, in sea-water, as they are broken off from 

 the parent rock respectively, whether at the time or at the 



