Z04 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 
Shell consisting of 2 valves, superior and inferior in position; ridge 
present, forming continuation of tail. The tail in this species is a 
shell process, consisting of 2 halves, a superior and an inferior, each 
connected with and forming a solid process of the corresponding valve. 
Length of tail, 38 4.. Valves separating very slowly in sulphuric acid 
(cold, concentrated), the gradual lateral shifting of one valve over 
another beginning within a few minutes and continuing for 20 or 30. 
Coincidently the two tail halves diverge, serving well a§ indices of the 
amount of lateral shifting of the valves. Iodine fails to loosen the 
connection of the tail (or of either half) with the valves. 
Capsules long, narrow, parallel-appressed; capsular index about 0°40; 
walls rendered transparent and filaments visible by iodine water. 
Sporoplasm showing the usual anterior extension of the supero- 
median cornu. The other cornua are also recognizable. Vacuole pres- 
ent, subcircular in outline, usually placed toward the anterior end of 
the sporoplasm. As regards nuclei, hydrochloric acid alcohol carmine 
always stains as many as and usually 2, rarely 3; position inconstant, 
one or both being either before or behind the vacuole. In addition, 
there are constantly present, at or close to the extreme posterior end 
of the sporoplasm, 2 deeply stained dots, which are too minute to show 
any structural details. 
Habitat.—7 or 8 cysts at bases of the spines of the second dorsal fin 
of Ameiurus melas Raf. (bullhead) from Storm Lake, Iowa, collected 
August 23,1890,by Prof. Seth EK. Meek, to whose kindness I am indebted 
for the specimen. 
This species can only be compared with the next. The following 
summarizes Miiller’s scanty diaguosis of that form: 
Body very narrow, 3 to 4 times as long as broad; capsules parallel- 
appressed; tail simple, oceasionally double. 
The present species answers to all of these characters, but they are 
too few to warrant the fusion of the two forms, although their identity 
may be strongly suspected. If established, their identity would con- 
stitute a very interesting fact, both in zoological and in geographical 
distribution, for we should then have a species found (so far) contined 
in its zoological range within the Stluride and with a very wide geo- 
graphical distribution.! 
1 For the geographical distribution (in South America) of 2. seba and of P. fasciatum, 
see Kigenmann & Kigenmann, Revision So. Amer. Nematognathi (Occas. Papers Calif. 
Aead. Sci., San Franc., 1890), pp. 123, 209. Considering the names used by Miiller, 
the date of his writing, etc., it seems rather probable that his localities were those 
known to Cuvier and Valenciennes (1840), viz, for 2. sebw, Surinam, Cayenne, Rio 
Janeiro, Buenos Ayres, and for P. fasciatum, Surinam. ; 
, 
