NORTH MIERICAN PARASITIC COPEPODS.— PART 9. THE 



LERN^OPODIDyE. 



By Charles Branch Wilson, 



Department of Biology, State Normal School, Westfield, Massachusetts. 



DEVELOPMENT OF ACHTHERES AMBLOPLITIS KELLICOTT. 



INTRODUCTORY. 



The present paper is the ninth '^ in the series deahng with the North 

 American Parasitic Copepods. It takes up the development of a 

 species which is the American representative of the European Acli- 

 theres percarum Nordmann, and which may serve as the type of the 

 family Lernseopodidse. 



This American species is very common upon the gill arches of the 

 rock bass or red-eye, Amhloplites rupestris, and is occasionally found 

 upon other species of the Centrarchidse. 



At the present time it has never been obtained from the American 

 perch, or from any other of the Percidse. 



It lives fastened to the inner surface of the gill arches and easily 

 escapes detection, especially in the larval stages, by concealment 

 among the large teeth which cover that portion of the arches, and 

 by being covered with the slime that envelops the whole of the gill 

 surfaces. 



The surest method of detecting its presence and the one by means 

 of which all the larval stages here described were discovered, is to 

 cut out the gills carefully, separate each arch from the others, and 



a The other eight papers are as follows: 1. The Argulidse, Proc. U. S. Nat. Mus., 

 vol. 25, pp. 635-742, pis. 8-27. 2. Descriptions of Argulidae, idem, vol. 27, pp. 627- 

 655, 38 text figures. 3. The Caliginae, idem, vol. 28, pp. 479-672, pis. 5-29. 4. 

 The Trebinse and Euryphorinse, idem, vol. 31, pp. 669-720, pis. 15-20. 5. Addi- 

 tional Notes on the Argulidse, idem, vol. 32, pp. 411-424, pis. 29-32. 6. The Pan- 

 daring and Cecropinte, idem, vol. 33, pp. 323-490, pis. 17-43. 7. New species of 

 Caliginaj, idem, vol. 33, pp. 593-627, pis. 49-56. 8. Parasitic Copepods from the 

 Pacific Coast, idem, vol. 35, pp. 431-481, pla. 66-83. 



Proceedings U. S. National Museum, Vol. 39— No. 1 783. 



189 



