Til. COTTOIDS OF NORTH AMERICA. 13 
they are only accidentally taken either with the hook or the net, and must be, as 
already remarked, sought for under stones. In the United States where the 
markets are abundantly supplied with larger fishes, the Miller's Thumbs pass 
entirely unnoticed. 
Some species spawn in the spring, others in summer, from the month of March 
to July. When only one species was admitted in both continents, the difference of 
latitude in America was called on to explain the difference in spawning. Thus, to 
see the Cottus of the State of Connecticut spawn in March and April, and those in 
the Great Bear Lake only in May, appeared quite natural. But how explain the 
fact, that in the Seine, at Paris, the C. gobio spawns in May, June, and July, 
whilst in the State of Connecticut it spawns in March and April? The isothermal of 
Paris, it is well known, passes below that of any part of Connecticut. The Cotti 
of the Danube again, spawn in March and April. 
It has for a long time been known that certain fishes construct nests, such as 
Sticklebacks. Others take care of their spawn and young; so do the lump-fish, the 
cat-fishes, and, according to Fabricius, the male of his C. gobio does the same. We 
know nothing of the behaving of other Cottoids in this respect. 
The food of Cottoids consists generally of crustaceans, insects and of their larvee. 
Fabricius says that his C. gobio feeds on ammodytes (Sand eel) Holothuria priapus 
(Sea cucumber), worms and small fishes. Sir John Richardson tells us that frag- 
ments of small fish were found in the stomachs of C. cognatus. We have examined 
the contents of the stomach of many marine and fresh water Cottoids, and in the 
Acanthocotti of the Boston Bay found them to consist of crabs (Pilumnus Harrisit) ; 
in Cottus viscosus and gracilis, of insects and larvee, and in Triglopsis Thompsonii 
of shrimps. We have never found any indications of fishes. 
