520 THE AMERICAN NATURALIST. [Vol. XXXVIII. 



The anal segment or pygidium shows no enlargement nor 

 other peculiarities exhibited by most species of Polygordius. 

 There are no marginal papillae or special appendages of any 

 sort, but the pygidium continues the general outline of the rest 

 of the caudal region to the anus. The caudal setae evidently 

 serve the same purpose as the bulbous enlargement with its 

 papillae of Polygordius in anchoring the posterior end of the 

 worm. For this worm the name of ChcEtogorditis canaliailatus 

 is proposed. Its chief interest is that it somewhat bridges the 

 gap between Polygordius and the Polychaeta and partially con- 

 firms the view expressed thirty years ago by Mcintosh that 

 Polygordius finds its nearest polychaste relations in the Ophe- 



The First Steps Toward Degeneration 2n the Parasitie Cope- 

 pods : Charles B. Wilson, State Normal, Westfield, Mass.— No 



Gyvtnandromojphous Ants; W. M. Wheeler, American 

 Museum of Natural History.— No abstract. 



Trematode Parasites of American Frogs: H. S. Pratt, 

 Haverford College.— Up to the present time the following 

 species of trematodes have been found in American frogs :— 

 Halipegns {Distomuni) ovocaudatns Vulpian in the mouth and 

 eustachian recesses; HeBmatolcechns {Distomnin) longiflexns 

 Staf., H. similiplexHs Staf., H. breviplexus Staf., H. vario- 

 plcxus Staf., and Ostiolum {Distomnm) formosum Pratt in the 

 lungs ; Pleurogenes {Distomnm areanus Nickerson encapsuled 

 in the pylorus and the liver; Distomnm qnietnm Staf. Cepha- 

 ogommns americanns Staf., D. retusum Leidy, and Holosto- 

 mum nitidum Leidy, in the small intestine : Diplodiscus 

 {Amplnstomnm) snbclavatns Goeze in the rectum ; Gorgodera 

 {Oistomum) avipUcava Looss, G. simplex Looss, G. attenuata 

 ^"^^ ^'-^^nslneida Staf., in the urinary bladder; Disto- 

 mtetraevstis Gal. encapsuled in the muscles of the throat ; 

 and Monostomnm ornatnm Leid}- in the bodv-ca\-itv. 



Development of the Compound Eye of the 



