22 PAPERS ON ZOOLOGY OF MICHIGAN. 



(3). In August the shoal fishes are generally most abundant where 

 there is most aquatic vegetation. 



(4). Fish enemies in the form of parasites appear to be very frequent 

 in the lakes examined. 



(5). South Twin Lake is one of the northern lakes that may be 

 advantageously studied to determine its suitability as an environment 

 for the black bass. The young evidently thrive there, and one of size 

 was caught which was in very good condition. The many minnows 

 in the lake might furnish a large quantity of available food for the bass. 



LIST OF SPECIES. 



The following list comprises only the species actually secured or ob- 

 served by the writer, and, as has been said, is principally confined to 

 the shoal species. ■ It is of course incomplete, but it contains additional 

 data on the distribution of the species. The nomenclature and the 

 order of consideration are, with a few modifications, those used in 

 Jordan and Evermann's Fishes of North and Middle America. The 

 millimeter numbers given refer to the length of the fish, which was 

 taken from the tip of the snout to the posterior end of the caudal fin. 



1. Catostomus catostomus (Forster). Long-nosed Sucker. — Found 

 only in Twin Lakes, where it appeared to be common. 



2. Catostomus commersonii (Lacepede). Common Sucker. — A single 

 small specimen (36 mm.) taken from South Stonington Lake. 



3. Chrosomus erythrogaster Rafinesque. Red-bellied Dace. — Com- 

 mon in both Twin Lakes and in each of the two Stonington Lakes ex- 

 amined. In the latter, it was found schooling with Pimephales promelas. 

 The specimens collected measured 21-63 mm. One fish with bright 

 red under-parts was found. 



4. Pimephales promelas Rafinesque. Fat-head Minnow. — Taken 

 only at Stonington, where it was abundant in both of the lakes studied. 

 Two hundred and four specimens (22-60 mm.) were collected. Three 

 were found with cestodes (probably Ligula) filling their body-cavities 

 and greatly distending their abdomens. 



5. Pimephales notatus (Rafinesque). Blunt-nosed Minnow. — Found 

 only at Bear Lake, where thirteen were taken (24-35 mm.). 



6. Semotilus atromaculatus (Mitchill). Horned Dace. — The horned 

 dace was only observed in Twin Lakes where it was abundant. Only 

 small specimens, 60-70 mm. long, were found on shoals, but large ones 

 (100-155 mm.) were in streams close to the lake. The fish were much 

 infested with a protozoan parasite, Myxobolus, which produced whitish 

 swellings of the skin and often made the fish conspicuous. Of the two 

 hundred and thirteen specimens preserved, thirty-five were diseased 



