MUSEUM OF COMPARATIVE ZOOLOGY. 271 



Annelids make up the greater part of this collection. Of other worms 

 the Nemertinse are represented by isolated fragments which do not ad- 

 mit of closer detailed description or identification ; they are mainly 

 littoral forms from Key West, from No. 5, and from " Sigsbee " No. 9, 

 and off Havana 1 75 fathoms ; none from the deep-sea stations. One 

 single species of Sagitta found off Havana in 480 fathoms (Sigsbee) is of 

 course not to be ascribed to that depth, but was undoubtedly brought 

 up in the net by mere chance. 



Gephyreans are represented in the collection by Sternaspis, Sipunculus, 

 Aspidosiphon, and Phascolosoma : Sipunculus littoral from Bahia Honda, 

 Sternaspis sp. from a depth of 158 fathoms, Aspidosiphon from 190 

 fathoms (No. 23), while many still undetermined species of Phascolo- 

 soma are littoral, and extend as far as the greatest depth here recorded, 

 one species of Phascolosoma having indeed been brought up in a Denta- 

 lium shell from a depth of 15G8 fathoms. 



Although so numerous, these worms have but a slight significance as 

 compared with the Chsetopods of the collection. The occurrence of 

 Chaetopods in certain localities where the animals themselves are not 

 found, may be inferred by the presence of their tubes. Yet such a 

 conclusion is not always admissible without further evidence ; at least 

 only when the individual worm builds his tube in so characteristic 

 a way that there is no possibility of mistaking it for that of other 

 Annelids.* When no foreign material is used in the construction of the 

 tube except mud consolidated by the secretions of the worm, the tubes 

 of very different species of worms may have a great similarity among 

 themselves; when, on the contrary, various foreign materials are cemented 

 in the tubes, such marked peculiarities may occur in their choice and 

 application that from a fragment of the tube the builder can be inferred 

 ■with as much certainty as the snail from the form of his house ; the 

 form of the tubes may even be so peculiar that there is no danger of 

 mistaking them for other tubes. Examples of this kind occur in the 

 present collection, especially in the Eunicidte, but also in the Maldanidse, 

 Sabellidte, and Serpulidse. In determining the distribution of the 

 worms, the data furnished by the tubes must always be used with great 

 caution ; for it must be remembered that uninhabited tubes may be 

 carried away by currents ; in such instances they would usually be 



* Several times I found tubes in the Hassler collection whicli from their whole ap- 

 pearance I should have taken for worm-cases ; but the inhabitant was a Crustacean 

 (Amphipod). I cannot decide whether in this case the occupant of the tube was also 

 its builder. 



