378 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
however, do away with its practical value as an index of slight differences — differ- 
ences so slight as to make it probable that the forms exhibiting them intergrade and 
interbreed, or would interbreed, with the type. 
Microscopic sections sufficiently good to show the plan of the canal system (in 
particular the size, shape, and connection with exhalent cavities, of the flagellated 
chambers) are necessary for the diagnosis of most horny and calcareous sponges; less 
necessary for the silicious forms. 
For the study of the skeleton: (1) It is sometimes necessary to bisect the whole 
sponge in order to learn the relative arrangement of internal and peripheral portions. 
(2) The arrangement of spicules, spieulo-fiber, or horny fiber, may best be learned 
from thick sections. These may conveniently lie cut free-hand after a very short 
imbedding in paraffin. Warm turpentine dissolves the paraffin very quickly, and 
the sections may be mounted in balsam. (3) For the demonstration of horny matter 
where scanty (as in certain chalinine sponges) and for the study of Ilircinia filaments, 
glycerin preparations are far superior to balsam ones. (I) In the case of the horny 
sponges it is advisable to prepare macerated skeletons as well as sections. Warm 
carefully a piece of sponge or a thick slice in caustic potash, not allowing fluid to boil. 
Leave in the fluid until the skeleton can be cleaned by gently squirting upon it 
with pipette. (5) In the case of silicious sponges the arrangement of the skeleton 
may often be learned in a somewhat similar way. Warm a thick slice in potash, not 
allowing the slice to disintegrate; compress between slide and cover, admitting fresh 
water into the space until the skeleton has been cleared of the macerated debris. 
(6) Surface preparations of the ectosome are usually necessary; surface layer may 
be stripped or sliced oil'. (7) For a study of the individual megascleres it is only 
necessary to boil a bit of sponge in potash, wash, and examine the sediment. Micro- 
scleres are often overlooked in this way. For the microscleres a small piece may be 
boiled on the slide, though I prefer to make a section, or dehydrate and soak in clove 
oil a fragment, teasing it then on the slide and mounting in balsam. 
Unless special mention is made, measurements of spicules given are the average 
maximum measurements, the diameter given being the greatest diameter of spicule. 
Colors mentioned are those of alcoholic specimens. 
Stations at which sponges were obtained. 
Station 
No. 
Locality and exact position. 
(All compass bearings magnetic.) 
Depth 
(fms.). 
Bottom. 
Dredging instru- 
ments used. 
6056 
Oil Aguadilla, Punta de Borinquen light-house NE. I E. 31 miles . 
48 
Sand, mud, 
shells. 
Dredge. 
6063 
Mayaguez Harbor, Punta del Algarrobo E. 2} miles 
75 to 76 
Rocky, sand, 
and coral. 
11-foot beam trawl. 
6007 
Mayaguez Harbor, Punta del Algarrobo E. by N. I N. 5J miles 
97 to 120 
Coral 
Dredge. 
6070 
Mayaguez Harbor E. f S. 9 miles 
220 to 225 
ltockv 
9-foot beam trawl. 
6072 
Oil Punta de Melones, Cabo Rojo light-house SSE. 5) miles 
7? 
Coral, sand, 
shelly. 
Tangle. 
6075 
Boca Prieta, Punta Guaniquilla SSE. 31 miles 
8i 
Coral, sand . . 
Do. 
0076 
Oft Gallardo Bank, tangent of Morillos de Cabo Rojo ESE. } E. 
9, miles. 
10 
do 
Do. 
6079 
20 to 23 
Coral 
Do. 
6080 
20 
23 
do 
Dredge. 
Tangle. 
6088 
OfT Vieques, Sail Rock NE. I N. 10} miles 
....do 
6090 
16 
....do 
Do. 
6097 
Oil Humagao, village of ilucares N. } W. 51 miles 
i°_ 
do 
Do. 
In some cases the specimen label did not bear a station number, reference being 
made to a named locality. A query (?) has been put after Station in cases where 
there was no label or the station number had been effaced. 
