Til i: .V>.\AI>S 



AND 



MAiiAZINE OF NATUliAI. lllSTOltY 



[SfKTd SErtlKS.] 



" pprlitora sparuite iniiscum, 



Nniados, i-t circiini vitn-os coiisi<lit<» foiitcs: 

 Pollice virginco teiHTos liic unrpite flort's: 

 Floribiis ft piftiini. divip, rcpli-te canistriim. 

 At vos. o Nyniplice Cratcrides, iti' sub uiidas ; 

 lie, rec-urvato variatii corallia trunco 

 Vfllitc miisoosis e rupibus, ft iiiibi coiioliaa 

 Ferte, Dea; pelagi, et pinfjui ooiichylia sueco." 



Jf. Purthenii Giannetlatii Eel. 1 , 



No. 73. JANUARY 1894. 



T. — On certain Tloines or Tuhes formed hy Annelids*. Bj 

 W. C. M'iNTOsii, M.D., LL.D., F.E.S., &c., Professor 

 of Natural History in the University of St. Andrews. 



]\Iany marine animals are known whose protective shells — 

 insignificant in themselves — form deposits of great extent 

 on the surface of the earth. Such, for example, are the 

 minute calcareous tests of the Foraminifera, and the equally 

 small but exquisitely beautiful siliceous skeletons of the 

 Kadiolarians. Moreover, by the tissue-secretions of the coral- 

 forming polyps in the warmer seas, islands, as well as large 

 additions to continental land, have been and are now being 

 constructed. In other groups, again, this liabit of making- 

 shelter is more or less in abeyance ; thus the Echinoderms — 

 though cons])icuous by the calcareous nature of their skins — 

 very rarely form a protective covering, almost the only 

 instance being the Holothurian called by Dalyell the Spinner 

 [Ilolothuria nigra), which makes a home for itself by an 

 abundant secretion of threads of mucus. Amongst the 

 Crustaceans a few construct tubular dwellings for themselves ; 

 and one species {Cerapus)-\ likewise adds long filamentous 



* Part of tlie Introductory Lecture to the class of Natural History, 

 October 1893. 



t l^ide Ann. Nat. Hist. ser. 5, vol. xvi. p. 484, pi. xiii. fig. !). 



Ann. & Mag. N. Hist. Ser. 6, Vol. xiii. 1 



