24 GENERAL FEATURES, MP:TH01)S, ETC. 



tory mentioned in the introduction. However, it cannot be said that in any 

 case we have any very definite information rej^arding the ^pogjnxphical limits 

 or relative abundance of a single sj^^cies. 



There is httle to be said regarding the vertical distribution nf the species 

 described in the present paper. Where several individuals have been secured 

 from a numlx'r of stations eacli species appears to l)e restricted (n a fairly definite 

 deptli. ChartixlentKi iiiliduluin is re])()rted to have a range of from 14-1250 

 meters. A much greater depth may be jiossible for ('. hawaiiinsis from Station 

 4130 where the initial sounding recorded 13t)2 fms. ; but since the closing sound- 

 ing was 358 fms. it is probable that the latter figure is more nearly correct, as a 

 second specimen was taken at a depth of 528 fathoms (Sta. 395)2). In many 

 places the ocean floor is exceedingly rougli and characterized by high almost 

 vertical cliffs bounding fissure-like valleys. Ihider such circumstances a num- 

 ber of soundings are desirable in order to a\'oid the necessity of accepting great 

 extremes in vertical tlistribution though these may in reality exist with certain 

 species. 



Mode of life, Food. — The species belonging to the Chaetodermatidae 

 are, so far as known, inhabitants of the sea bottom where they excavate burrows 

 which they rarely l(>ave. Wiren ("!)2) who kept over one hundretl specimens of 

 C. niliduluvi in captivity says they progress through the ooze by means of the 

 alternate contraction ami expansion of the prothoi'ax aided by movements of 

 the entire body; and that when at rest they ordinarily tlirect the liody vertically 

 with the cloacal chamber widely expanded, and the branchiae fully cx])osed at 

 the opening of tln^ biu'row at the siu'face. When disturlied they disajipear 

 instantly several inches into the nuiil. In most respects these observations 

 answer for ('. cruiVttd which I kcjjf some time in cajitivity. This animal from 

 time to time advanced through the ooze in the manner described liy Wiren but 

 it never appeared at the surface. For hours together it remained ([uietly in its 

 burrow with the gills fully expaiuled and when disturbed retreated but slowly, 

 though the gills were at once retracted and the cloacal chamber closetl. The 

 indivitluals acting in this manner were apparently in a normal condition since 

 the alimentary canal of several kept in cajitiNity for nearly one month contained 

 tjuantities of food. 



The members of the suboi'dci' Neomeniina, on the other hand, are not 

 known to bun'ow, Init are usually found on some species of hydroid, coral, and 

 exceptionally (Proncomcnia vagans, P. desidei-ata) , on plants. Now and then 

 specimens have been dredged unattached and it may be that they, like Ncor7icnia 



