260 BULLETIN OF THE UNITED STATES FISH COMMISSION. 
color. Such swarms would readily attract the schools of rapidly swim- 
ming fishes, while they might easily escape the notice of a fishing-vessel 
moving slowly from place to place. It is also probable, from previous 
observations of the Fish Commission, that the mackerel feeds to some 
extent below the surface. 
As to the character of its food the mackerel probably exercises little 
discrimination, but swallows all the smaller objects occurring in its path. 
Certain species or groups of species are, however, much more abundant 
than others, and these are recognized as its common or appropriate 
food. Such are the copepods, the pelagic amphipods, some of the ptero- 
pods, and perhaps Sagitta. On the present cruise several species of 
copepods, Themisto bispinosa of amphipods, Spirialis , sp. of pteropods, 
and Sagitta elegans were the most common and wide-spread, and they 
were all abundant in the stomachs examined. 
A list of the forms identified from the towings and an account of the 
contents of each towing are given below. In the hasty examination 
made, many species have undoubtedly escaped notice, and the lists should 
be regarded as containing only the more common or more conspicuous 
forms. But few jelly-fishes, representing only two genera and species 
of small size, were preserved, though other forms were taken by the 
schooner. Sagitta was often very abundant, but annelids were exceed- 
ingly rare, and not more than three or four species were observed. Of 
copepods Temora longicaudata was identified from most of the towings ; 
Calanus , sp., was nearly as wide-spread, and often more abundant ; Gen - 
tropages typicus was very common ; Pleuromma , sp., composed the bulk 
of one of the towings, and two of the smaller lots consisted almost ex- 
clusively of Anomalocera Patersonii. Themisto bispinosa , of amphipods, 
was nearly always present, and sometimes in great abundance, though 
often young and small; Galliopius Iceviusculus occurred only in Fort 
Pond Bay, Long Island, and Narragansett Bay. Isopods were rare and 
represented by only one genus, Idotea, of which three species were taken, 
one, however, only in Narragansett Bay. The Schizopoda and Deca- 
poda were represented by young stages only. Of pteropods, Glione 
limacina was moderately abundant at times, while Spirialis was often 
very common, in some cases composing a large proportion of the bulk 
of the towing. Salpa Gaboti occurred only in one instance. The eggs 
and embryos of fishes were sometimes abundant, but there was seldom 
any trace of vegetable life, except in the rare occurrence of small de- 
cayed fragments, apparently of eel grass, Zostera. An interesting 
feature was the finding of so many species of insects blown or drifted 
from the shore. Seventeen species belonging to four orders were taken, 
but each species was represented by only one to four specimens. 
Prof. S. I. Smith kindly examined the amphipods, schizopods, cuma- 
cea and decapods, and has furnished such identifications as are given. 
Mr. J. Walter Fewkes has determined the Medusae, Mr, William 0. 
Dali the Mollusca, and Mr. John B. Smith the insects. 
