gp:neral features, methods, etc. 23 



Occurrence. — Owing to the methods employed the Solenogastres de- 

 scribed bj' the earher authors, and a small fraction of those subsequently dis- 

 covered, have been taken in comparatively shallow water, in a very few cases 

 within the littoral zone. However it cannot be said that thej^ are essentially 

 shore forms, for the various deep-sea explorations of recent years have demon- 

 strated that, in certain localities at least, thej- are a characteristic feature of the 

 deeper regions of the sea and only exceptionally extend into habitats along shore. 



With the publication of the present paper the number of species of Soleno- 

 gastres reaches a total of ninety-two. In most instances these have been de- 

 scribed from one or at most a very few specimens, but the scantiness of material 

 appears to be the combined result of habitat and mode of capture. As men- 

 tioned in a succeeding paragraph, these animals are either attached to some 

 coelenterate host or they burrow in the bottom ooze. In the first case they may 

 be readily dislodged and lost; in the second they are usually out of reach. On 

 several occasions, while acting as temporary naturalist on the U. S. F. C. Str. 

 "Albatross," I have been able to examine carefully large quantities of mud, 

 which has been scooped from the bottom, and have secured unusually large 

 numbers of individuals of a few species. In Alaska (Sta. 4264), for example, 

 the dredge load contained forty-seven specimens belonging to two different 

 genera (Limifossor iaipoideus and Chaetoderma erudita). Again in Monterey 

 Bay, California, one haul (Sta. 4522) contained fifty-nine Chaetoderma monterey- 

 ensis, while in a neighboring locality (Sta. 4523-4525) eighty were taken. In the 

 National IMuseum I recently examined a large number of small animals taken 

 by the '"Albatross" in the Atlantic, and discovered no less than thirty .specimens 

 of these molluscs belonging to two genera. From such data and considering 

 that the amount of territorj- explored is but a tithe of the entire sea floor, it is 

 reasonable to .suppose that in point of numbers and of species these animals 

 will far surpass their nearest allies, the Chitons. 



Owing to the fact that up to the present time no Solenogastres have been 

 reported from the North Pacific, and since the species described in the present 

 paper have usually been collected from widely separated stations in a single 

 dredge haul, it follows that there is little to be said definitely regarding their 

 general distribution. It is an interesting fact that of the eight species taken 

 in Japan six belong to the genus Strophomenia. The genus Limifossor is 

 represented by two species off Alaska and California respectively. This last 

 named region is likewise the home of Alexandromenia agassizi and .4. valida. 

 Species of Chaetoderma occur in the ooze in all of the carefully explored terri- 



