346 
BULLETIN OF THE BUREAU OF FISHERIES 
temperatures. However, the large majority of the forms collected seem to be more 
southern forms. 
It is evident, also, that many of the species of annelids are distributed through 
waters of widely differing salinities, as examples, Nereis limbata, Goniada oculata, 
Pedinaria gouldii, and others. 
Undoubtedly some of the annelids collected were living in situations which were 
not well suited to them, since the currents during fall and spring tend to carry plankton, 
including worm larvae, far up in the bay. Under those conditions a worm which lives 
at its best in water of a high salinity might have its larvae carried to regions of low 
salinity where they would settle down and continue to live, although under unfavorable 
conditions. 
Only one species representing the Hirudinea has been taken in our collections, 
and this one has been identified through the courtesy of Dr. J. Percy Moore, as the 
fish-leech, Piscicola punctata (Verrill). 
ARTHROPODA 
CRUSTACEA 
COPEPODA 
The free-swimming copepods of Chesapeake Bay and the region immediately 
outside the bay have been studied by C. B. Wilson. He has made the identifications 
and has studied the distribution of the various species. 
The results of his work show very clearly that only two or three species were 
present in sufficient numbers in the bay during our cruises to be of much economic 
value; that of these, 2 species, Acartia dausii and A. longiremis, were distributed over 
the whole bay from the region of Baltimore to the mouth of the bay throughout the 
year; that 10 species at least, including especially the 2 just mentioned, must have 
been able to accommodate themselves to a large range of salinities, since they were 
found all over the bay in addition to the ocean; and that there were 19 species caught 
outside of the bay between the 100-fathom line and the mouth, which were not dis- 
covered in our very numerous towings made throughout the year in the bay. The 
absence of these 19 species, which for the large part have been found outside of such 
bodies of water as Chesapeake Bay in other parts of the world, may be ascribed to the 
low salinity existing in the bay; but it is not possible at the present time to establish 
such an assumption absolutely as a fact, since our towings outside of the bay were 
made only during the August, 1920, cruise. Furthermore, there are numerous other 
factors, such as presence or lack of the proper kind of food, associations with other 
forms- — for example, Sapphirina gemma , which is a commensal in Salpa, light, depth, 
temperature, etc. — which might have to be taken into consideration. 
"Wilson’s studies have brought to light the following species from Chesapeake Bay 
and the region just outside of the capes. He has divided them into groups according 
to their distribution. 
UNIVERSAL IN BAY AND OUTSIDE 
Acartia clausii Giesbrecht, A. longiremis (Lilljeborg), Centropages harnatus (Lilljeborg), C. 
typicus Ivr0yer, *Harpacticus gracilis Claus, Oithona brevicornis Giesbrecht, 0. similis Claus, Para- 
calanus parvus (Claus), Pseudocalanus elongalus (Boeck), Pseudo diapiomus coronatus Williams, and 
*Microthalestris littoralis G. O. Sars (the last species is pronouncedly littoral and was not found in 
the collections made outside). Two other species, Labidocera aestiva Wheeler and Ectinosoma cur- 
ticorne Boeck, were almost universally distributed. 
