28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



sitic feeding habits of many of them, sucking on the body of other 

 larger animals. Thus some Phanodcnna-like nematodes were found 

 by Ditlevsen (1927) partly buried in the body of Polychaeta. The 

 writer (Filipjev, 1927) found a Phanodermopsis with the muscu- 

 lature of the esophagus and nearly all other organs degenerated and 

 apparently not functional except for the genitalia, which also gives 

 a hint of their parasitic nature. Solenolaimus and Siphonolaimus 

 have a very dark reddish intestine which is explained by Zur Stras- 

 sen as resulting from their feeding on polychaete worms. The 

 writer found in Neva Bay Dorylaimiis stagnalis with the intestine 

 colored quite as are the Oligochaeta in the same habitats. The en- 

 tire group of Mermitidae passes most of its larval life and all the 

 time of feeding inside insects or some other invertebrates. Odon- 

 tobiits ceti, a linhomoeid, is found, according to Baylis, in the mouth 

 of whales, although rather in saprozoic than in parasitic conditions. 

 The soft cuticle of all Linhomoeidae suggests that they may be lib- 

 erated from a host after the fashion of the Mermitidae. It would 

 not be surprising if the young or larvae of some parasites, especially 

 those of marine fishes, would be found very like some free-living 

 marine genera, thus giving a key to the phylogeny of certain para- 

 sitic groups. 



The same idea was recently expressed by WUlker (1929) but 

 probably he was not entirely happy in the material selected for com- 

 parison (cf. pp. 195-196). 



Order ANGUILLULATA 



As has been said, most of the saprozoic and terricolous forms 

 of this order are very different from the foregoing groups in their 

 physiology. The cuticle is very impermeable and does not allow the 

 substances of the external medium to penetrate. This explains the 

 strange fact that many forms of this order can live for hours in such 

 fluids as corrosive sublimate, formaldehyde or osmic solutions cap- 

 able of killing other animals in a few seconds. The ordinary vinegar 

 eel lives even normally in a medium that would be fatal for most 

 other animals. Possibly it is the same lipoid cover that was investi- 

 gated by Zavadovsky in the eggs of Ascaris that preserves these 

 forms. 



One of the features of this order is the absence in nearly all 

 of them of the setae on the head and the whole body, these being re- 

 placed by papillae ; generally the latter are not very prominent aside 

 from the genital papillae of the male. The amphids have a very 

 reduced size and their existence was established with certainty only 



