18 PROCEEDINGS OF THE NATIONAL MUSEUM vol.80 



armata, and the two species of Acartia, with A. longiremis more 

 abundant than A. clausii at the 100-fathom line but less abundant 

 nearer the shore. Of these seven species most abundant in the ocean, 

 only one, Metridia lucens, was not also found in the bay. 



The other oceanic species require but little comment. Calanus 

 helgolandicus was present in considerable numbers in the bottom nets 

 hauled from depths of 40 and 20 fathoms. The Corycaeus species 

 are minute and appeared only in the surface net at the 100-fathom 

 line. Macrosetella gracilis^ Euchaeta norvegica, Mecynocera clausii^ 

 Oithona plumifera, and Rhincalanus nasutus are all oceanic forms 

 not likely to be found in the bay unless at the mouth. Candada 

 m^nata might properly be included with these oceanic species, since 

 it was found in the 10, 40, and 100 fathom hauls. The few specimens 

 obtained in one of the bottom nets at Station S in the inner bay 

 were evidently exceptional. 



The fact that three of the Corycaeus species were found in the 

 outer bay suggests that it is not impossible for some or all the other 

 three species to appear there in the future. The new species of 

 Pontella is evidently a northern form since it has been taken abun- 

 dantly in surface tows at Woods Hole, Mass., during the summers 

 of 1923 and 1924. Clytemnestra, Euchaeta^ Mecynocera^ Metridia, 

 Oithona, Rhincalanus, and Macrosetella are all widely distributed 

 and are found in the Pacific as well as in the Atlantic Ocean. 

 Oncaea and the two Sapphirina species are not so cosmopolitan, but 

 the former genus and Sapphirina gevima have been found on our 

 Atlantic coast as far north as Marthas Vineyard. 



Some of these oceanic species have not been reported before from 

 our American coasts, and others have not previously been found 

 as far south as the mouth of Chesapeake Bay. These will each 

 be noted under the remarks given for the separate species in the 

 following pages. 



DISCUSSION OF THE SPECIES 



The classification of the Copepoda proposed by Sars appears to 

 be the simplest and most rational one thus far advanced. Accord- 

 ingly the species are here arranged in the four groups, or suborders — 

 Calanoida, Harpacticoida, Cyclopoida, and Caligoida — but since 

 this is an account of the species found in a definite locality and not a 

 systematic treatise, it seems wise to arrange the species in each group 

 alphabetically and to omit family, generic, and specific diagnoses, 

 except for new species or for those especially figured. 



