Narrative of Bahama Expedition. i6^. 



seemed to be jI/. iu)da[ii:> Rec\'e. M. fitlic^^cciis Sow rrby. and 

 M. ^onimn Gmel. ^ 



The class ScaphojKjda was ri'prcscntcd by a ix-autitul 

 Doitalimu, probabh' J), hujucalum W'rrill. This is a w liite 

 species, less curved than nian\' of the n'cmis. and niaikcd with 

 deep longitudinal fluting. 



A remark made by Dr. Dall. to the effect that hermit crabs 

 which inhabit straight shells are themselves bilaterally sym- 

 metrical, is illustrated bv a little hermit which had taken up 

 its abode in one of these tube-like structures of the Doila- 

 lium. Upon remo\-ing tiie crab, it was foimd to he as r.traight 

 and symmetrical as any normal Crustacean. 



The reason for the beautiful surface ornamentation of manv 

 of the deep-water mollusks is not plain. It seems vmlikelv 

 that the light produced by phosphorescence or otherwise 

 could make it possible for these beauties to be seen, even if 

 the molluscan eye were capable of such discernment, h. cer- 

 tain beaut\- is of course imparted to these shells by tlieir \ery 

 delicacy, but the purely superficial lines and bead-like orna- 

 mentation is beautiful, aside from any quality of texture. 

 Perhaps the best suggestion bearing on this point is m<".de b\- 

 Dr. W. H. Dall in the admirable discussion with which lie in- 

 troduces his report on the Mollusca of tlie •• Blake." lie says: 

 •• Much of the sculpture which is presented by the deep-sea 

 species is particularly beautiful from its delicacy. There 

 seems to be an especial tendency to strings of bead-like 

 knobs, revolving striee and threads, and delicate transverse 

 waves. It is particularly notable that many of the deep-sea 

 forms, among all sorts of groups indifferenth'. ha\e a row of 

 knobs or pustules following the line of the suture and imme- 

 diately in front of it. The representatives of the rock-purples^ 

 or Murices, a group wliich in shallow water frei[uent the 

 rocks and stonv places, and are then strongly knobbed or 

 spinous, retain a similar character in the deeps, but the pro- 

 cesses in question are extremely delicate or foliaceous, instead 



' The author is hc're, as elsewhere, indebted to Mr. 11. V. Wiikham for 

 tlie preliniiiiarv ;;iul approximate idetititication of Molliisid. 



