24 MUSSEL FAUNA OF MAUMEE EIVER. 



gi'ouijs of knobs opijosite each " shoulder " and extending from the hinge two- 

 thirds of the way to the edge of the shell. Three straight ridges, also salmon- 

 colored, on the left valve, radiating from the distal end of the row of knobs. 

 The salmon marks in the nacre corresponded exactly with the position of the 

 distomids in the mantle. There were three bunches of distomids corresponding 

 to the three ridges on the left side. 



No. 8. — Parasites: Distomum of Osboru, about 200 on the outside of the 

 mantle at the " shoulders," but no sporocysts present. Atax intermedius 14, 

 Atax aculeatus 3, and several examples of Atax ypsilopJiorus. The Atax con- 

 tained large eggs, and all the animals were located between the gills; Cotylaspis 

 insignis 2, in the axils of the inner gills; Aspidogn.Hcr conchicola 5, in the peri- 

 cardial cavity. There was a good deal of Plnmatclht poJi/itiorpha on the shell. 

 The color of the nacre was pretty uniform, but somewhat more intense in 

 the region of the unbones, where the distomids were also thickest. Alimentary 

 canal full of Trachelemonas, with a few diatoms and Scenedesmus. The 

 Trachelemonas were very actively swimming about, althougli they had been 

 in the stomach of the mussels for at least 36 hours. 



No. 9. — Parasites; Atax 23. between the gills; the eggs abundant, and some 

 yoimg hatched; Distomum of Osborn 3, on "shoulders" as usual; Cotylaspis 

 insignis 3, iu axils of inner gills; Aspidogaster conchicola 7, in pericardial 

 cavity. The alimentary canal contained rather numerous Scenedesmus, i 

 Fediastrmn pertusum, 4 Aniirwa cochlearis, and 1 spindle-shaped Euglena- 

 like object. 



In a day or two after the visit to the reservoir in which these 

 mussels were obtained, it was revisited. The pond was covered with 

 a green scum, but there was no opportunity to examine it more fully. 



The collections at this place were particularly interesting- because 

 of the knowledge obtained concerning stages in the life history of the 

 distomid of Osborn, sporocysts of which were especially abundant 

 in mussels no. 3 and 5. These matters are more fully discussed 

 under our notes on parasites toward the end of this report. (See 

 p. 61.) ^ 



Station FF. Feeder canal between the reservoir and the Maumee 

 River. — The feeder canal with its reservoir may be regarded as a 

 sort of auxiliary channel of the St. Joseph Eiver from Robinson Park 

 down to the city. The mussels were, however, much more evenly dis- 

 tributed in the canal bed than in the river bed. The latter was 

 examined from the reservoir of the canal down to the mouth of the 

 river, but only occasional mussels were obtained above Wagner Street 

 Bridge. 



Station G. St. Joseph River at Wagner Street., Fort Wayne.— 

 At Wagner Street there was a veiy good shell bed^ which was ex- 

 amined pretty thoroughly. The river here is shallow, with a gravel 

 bottom, and the current during ordinary stages of the water is 

 about 2 or 2^ miles an hour. 



A little below this station there appeared to have been a fair bed 

 of mussels; but sand was being hauled from the river in large 

 quantities, and the disturbance was unfavorable to molluscan life. 



