THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 183 



Hdhitat. — Subcutaneous tissue of all regions of the hodj oH Notroj)is 

 megulops Raf. (red finned minnow) taken in Ulack River, Lorain County, 

 Ohio, 6 miles above Lake Erie, September 1, 1890 (also October 5, 1891; 

 see below). Collector, Mr. L. M. McCormick. Identification by Dr. D. 

 S. Jordan. 



With this species of fish were taken JSfoturns miurus, Catostomus tercs^ 

 and Moxostoma macroh'pidotnm^ and, in the immediate neighborhood, 

 letaJnniH and lioecns. None of these, however, were affected. 



Effects. — The epidermis of the fish is sometimes marked by dark 

 purplish blotches. Scales are absent from the surface of the cyst iu 

 most cases, although a few were observed quite loosely attached to one 

 of the larger clusters. All of the fishes appeared to be in fair condition. 



Mr. McCormick has kindly furnished me the following additional 

 information : 



The fish were taken in the pool formed by Day's Dam, near the center of Sheffield 

 Township, Lorain County, Ohio. Although he has diligently exjjlored the streams 

 of Lorain County for material for his " Descriptive List of the Fislies of Lorain Co-nty, 

 0/iJO,'" he has never seen X megalops infested by this parasite except in this very 

 limited locality. The same day that specimens were first secured there he seined 

 Black River thorouglily from Elyria to below Day's Dam (distance 10 miles), but saw 

 no other diseased specimens. In spite of the admittedfallibility of negative results, 

 he believes this parasite to be restricted to a very narrow geographical range. Fish 

 first taken September 1, 1890 (about a dozen); a few more October 5, 1891 (the first 

 time of seining the pool that year). 



13. Genus et sp. incert. PI. 7, fig. 4. 



Psorosperms of Gasterosteus aculeatus, Lieberkiihn, 1854, Mnller's Archiv., pp. 

 9-10, 22, 24, 354-7, pi. 2, fig. 28, pi. 14, figs. 9-12. 



The following observations by Lieberkiihn relate to a puzzling form 

 found on Oasterosteus aculeatus (stickleback). His remarks are to me 

 somewhat obscure, and I am not certain that I always understand 

 his meaning. For that reason the translation is a literal one. 

 [Page 9] I am still iu entire ignorance as to what becomes of the psorosperms ol 

 Gas teros tens. In the skin of this fisb Gluge found cysts filled with entirely 

 structureless granules which had a marked similarity to those of the Gregarines. 

 Johannes Miiller has confirmed this discovery. I investigated about 100 cyst-bearing 

 specimens selected from a corresponding number of healthy stickleliacks. Among 

 10 fishes tliere was, iu tlie spring, about 1 available; in late autumn, on tlie con- 

 trary, only 1 in aboirt 100. The cysts varied greatly in size; the largest attract 

 attention at once, the smaller are only to be discovered upon close examination. 

 They have a very irregular form, mostly rod-shaped, and contain ordinarily the 

 structureless granules mentioned by Gluge. A few contained bodies with more defi- 

 nite structure and characters, reminding one of the iisorospcrms, for wliich reason 

 I will so name them. They are all nearly globular and somewhat smaller than the 

 ordinary psorosperms; they consist of a transparent membrane, within which 1 have 

 observed 3 kinds of contents, namely, in some a single small globule which is not 

 largo enough to come in contact with the membrane by its upper surface; iu others 

 lay, between the surrounding membrane and the upper surface of this 

 [Page 10] small globule, a small mass of exceedingly fine granules; in still others 

 the globule ajjpearcd to have divide^l, as 3 or 4 smaller globules were 

 present. Soveral of the smaller cysts contain^od a far more finely granular mass than 



' Bull. 2, Oberlin College, Ohio. 



