126 THIRTIETH REPORT ON THE STATE MUSEUM. [14] 



longing to the Diptera and aquatic in their habits), and after- 

 ward, in September, in the mucous lining of the intestines of 

 fishes, thereby, in .conjunction with the previous labors of 

 Grube, Leidy, and Meissner, clearing up their metamorphoses. 

 The larvae are tadpole-shaped. The habits of GORDIUS seemed 

 quite distinct from MERMIS found living in insects. 



Dr. Speyer communicates to me the information that the 

 occurrence of the Gordiacaea in the body of insects has fre- 

 quently been' observed in Europe, notices of which may be 

 found in several interesting communications from Yon Siebold, 

 in the Stettiner JEntomologische Zeitung for the years 1842, 

 -43, -48, -50 and -54. The species which infests most fre- 

 quently the Lepidoptera is Mermis albicans. They are found 

 in both the larvae and the perfect insects, oftener in the former. 

 They occur in the larvae which feed on tall trees, as well as 

 those which live on plants and low shrubs. Wet seasons 

 seem to be more productive of the parasitism, and Dr. Speyer 

 recalls, a number of years ago, during an unusually wet 

 season, his having met with several of such instances. From 

 an example of Hadena adusta he had a Mermis emerge, 

 of the length of eight and a half inches, and another from 

 Hesperia lineola after it had been pinned. Prof. Von Sie- 

 bold suggests that a heavy dew may moisten the trunks 

 of trees sufficiently to enable the Mermis to ascend them. 



The Mermis parasite (species not stated by Dr. Speyer) also 

 infests the Carpocapsa pomonella larvae in Europe. 



These pages have been for some months in type. In the 

 meantime, Dr. Packard's Report on the Rocky Mountain Lo- 

 cust, in Hayden's Geolog. and Geograph. Survey of Colorado, 

 for 1875, has been received. In it vpp. 663-667) he gives an 

 account of the several species of GORDIUS and MERMIS occur- 

 ring in the United States, transcribing from the paper above 

 cited (see full title below *), the descriptions of the Gordii and 

 also the history of Gordius aquaticus as given by Villot, car- 

 rying it beyond its encysted state in the intestines of fishes, 

 to its free and aquatic state the following spring. This stage 

 it attains by boring through the cyst into the intestinal cavity 

 of the fish, thence passing with the faeces into the water, where 

 material changes take place before it assumes the active stage. 

 For a more full account of these several transformations, see 

 p. 665 loc. cit. 



*Monographie des Dragonneux (Genre GORDIUS Dujardin), par A. Villot. (Archives 

 de ZoClogie experimental et generate, tome 3, No. 1, 2. 1874. Paris.) 



