CLASSTFKATIOX. 41 



I luivc I'diuul parallcliufi to soiiip cxlcnl the outer buccal sensory fold (]). 84). 

 Pru\dl lias noted that as some of these animals progress they inoxc the antei'ior 

 enil of the body from side to side, and appear to be using the organs in (|uesti(jn 

 to detect the character of their surroundings, so that they may be tactile. In 

 Ichthyomenia there are many pits, apparently ciliated, in the anterior end of 

 the body. These are probably sense organs, hut of unknown function. 



The buccal sensory plate in the Chaetodermatidae with its enormous nerve 

 supply may \-ery ]iro])ably function also as a tactile organ as Wiren and others 

 have assunuHl, but it is to be noted that while this structure takes an active 

 part in the excavation of liurrows it is ])robal)!e that it serves to detect the pres- 

 ence of food. At all events the alimentary canal of these animals is singularly 

 free from inorganic materials, and in th(> absence of any other well-defined 

 organs in or near tlie l)uccal cavit>' it is nol improbable that the plate acts as an 

 olfactory or more than usually delicate tactile organ. These same activities 

 or possibly the sen.se of taste have been assigned to the frontal sense organ noted 

 in the preceding paragraph. 



The dorso-terminal groove in the ( "haetodermatidae and its homologue in 

 the Neomeuiidae is usually consiilered to be an organ of special .sense, Heu.scher 

 alone alleging the contrary owing to the fact that the depression in Proncomenia 

 sluiteri was filled witli detritus. This condition is not infrequently encountered 

 in animals which have Ijeen excavated from the material in a dredge, but it is 

 certainly not a normal state of affairs. Concerning its function we have abso- 

 lutely no positive evidence. It is reported by Pruvot that it may hold the same 

 office as the frontal sense organ though the belief ajjpears to rest upon nothing 

 more tangible than a certain similarity of structure. 



CLASSIFICATION. 



While the modification, by Nierstrasz, of Simroth's scheme of classification 

 doubtless fails of necessity to indicate accurately the phylogcnetic relationships of 

 the Solenogastres it has the virtue of being more convenient than any other now 

 in use and hence has been adopted in large measure. The family name Para- 

 meniidae must be discontinued. Cockerell ('03) has shown that Pruvot's 

 genus Paramenia is preoccupied and has proposed the name Pruvot ina, hence 

 in the following table I have used a new family name Pruvotiniidae. The family 



