NATURAL HOSTS OF FRESH-WATER MUSSELS. 
105 
transportation of the infected fish, entirely feasible with some fish,“ would not be 
possible in this case, as the skipjack is very delicate and will not admit of handling 
during the warm summer months. 
SheepshEad {Aplodinotus grunniens). 
From its feeding habits we should expect to find this fish more often infected than 
any other species. In writing of it Dr. Forbes * says : 
This fish is of a sluggish habit, living on the bottom of muddy waters, where it feeds especially on 
mollusks, the shells first being crushed by the powerful, paved millstone-like, pharyngeal jaws. Often 
the stomach contains only the soft bodies and opercula of gastropod mollusks, the crushed shells having 
been thrown out. Crawfishes are also sometimes found in the food. Half-grown specimens feed largely 
on aquatic insects, especially the larvae of May-flies, mingling larger and larger proportions of mollusks 
with tliis food as they increase in size, until they come finally to depend almost wholly upon water 
snails and the relatively thin-shelled clams. 
As it is known to be the specific host for both L. Icevissima and P. donaciformis, it 
is of rather more than usual interest.'^ It can no doubt readily crush the papery shells of 
IcBvissima, and, from their small size, swallow^ entire the shells of donaciformis, from which 
we can readily understand the enormous numbers that are attached to the gills of 
this fish. 
The geographical range of the fish is given as “Great Takes to Texas and Georgia; 
abundant in all lakes and large streams west of the Alleghanies and east of the plains” 
(Jordan and Evermann). 
Simpson gives the ranges of the two mussels as follows: 
L. Icsvissima: “Mississippi drainage generally; eastern Texas, southern Michigan, 
western New York.” 
“Dr. Ortmann, in an interesting article in a recent issue of “The Nautilus’’ (vol. xxvi, p. 51), records the accidental intro- 
duction of the “ pocketbook ’ ’ (Z,. venlricosa) into the upper Potomac drainage in Maryland and West Virginia. 
6 Forbes, S. A.: Fishes of Illinois, Natural History Survey of Illinois, State Laboratory of Natural History, vol. in, p. 324. 
“ Since the above was written the author has had the opportunity to examine a number of fish taken by him in White and 
Cache rivers near Clarendon, Arkansas. During the first half of January (1913) 18 specimens of Aplodinotus grunniens were 
secured, eight of which bore natural infections, and from the number of glochidia borne by each fish I should accept it as the 
specific host of Lampsilis (Proptera) purpurata; five examples were infected on the gills and another both on gills and 
caudal fin. The cysts are very large and consequently very noticeable. While all are not of the same development the growth 
in the majority of cases is very marked; the infant mussels have assumed about the development indicated in the figure of Icevis- 
sima shown in figure 2, plate xxix. It is presumed these fish became infected some time during the autumn , but as many gravid 
mussels of this species, all with active glochidia. were taken during January, some may have become infected more recently. In 
these infections the number of infant mussels borne by individual fish varied from 68 to as many as 500 in two cases. The glo- 
chidium of purpurata resembles very closely that of L. {Proptera) alata both in shape and size, measuring 0.200 by 0.360 mm.; the 
hooks, however, are better developed than in alata. 
A still more interesting discovery is the finding of a number of glochidia of Quadrula heros, heavily encysted and of consider- 
able development, on the fins of two of these Aplodinotus. This glochidimn being of the hookless type it was naturally supposed 
to be a gill parasite, but this does not seem to be the case, as none were found on the gills of the fish. 
In the AVhite River material is also a specimen of rock bass {AnMoplites rupestris) carrying on its gills six glochidia of A radews 
ctmfragosa beautifully encysted and of considerable development. The hooked glochidium of Arcidens is closely related, in form 
at least, to the Anodonta group, one species of which {cataracta), according to Lefevre and Curtis (Bulletin U. S. Bureau of Fish- 
eries, vol. XXX, p. 158), would not metamorphose on the gills of the carp. A crappie {P. annularis) was also secured bearing the 
same species on the gills; but this mussel is probably more frequently found on the fins of fishes, as two hickory shad {Dorosoma 
cepedianum) were taken bearing considerable numbers on the fin margins, particularly the caudal, where they are deeply embedded 
in the epithelium. 
