318 THE ZOOLOGIST. 



sumes, refers merely to the appearance of the figures ; for nothing 

 appears to be known of the manner in which the threads are pro- 

 duced and attached. Adams's observations are referred to in 

 nearly all the books, and figures based on his are found in Wood- 

 ward and in Keferstein, that of the former having been repeated 

 by Fischer and twice by Tryon.* Mr. Tye, who refers to 

 Woodward, has by mistake attributed the observations to Ceri- 

 thidea decollata,i an animal which does not appear to fix itself by 

 threads, Dr. Gibbons having reported that large numbers seen 

 by him on trunks of marsh trees in Natal were attached, not by 

 threads, but by " a trifle of brittle mucus passing from the lip to 

 the tree," a mode of attachment, as Dr. Gibbons says, resembling 

 that of brackish water Littorince. t 



Planaxid^. 

 Planaxis has been listed among thread-making molluscs by 

 Dr. Macdonald,§ but the writer does not know on what authority. 



Solariid^. 

 According to Mr. Harper Pease, two forms of Torinia 

 (Hawaiian Islands) " suspend themselves by strong gelatinous 

 threads, one of which will sustain the weight of several shells, 

 and can be drawn out four or five inches"; the creatures are 

 found almost invariably upon branched coral. || 



PYRAMIDELLID33. 



Among the crowd of little conical-shelled molluscs of the 

 genus Odostomia, the use of a thread has been observed by 

 Jeffreys in Odostomia warreni, whose foot is remarkable from 

 being forked at the extremity like the tail of a Swallow. The 



"'Woodward, 'Manual of the Mollusca,' 1851, fig. 78: Keferstein, 

 ' Bronn's Klassen und Ordnungen des Thier-reichs,' iii. (1862-6), pi. lxxxii. 

 fig. 9 ; Fischer, « Manuel de Conchyliologie,' 1884, fig. 449 ; Tryon, ' Struc- 

 tural and Systematic Conchology,' ii. (1883), pi. lxx. fig. 73; 'Manual of 

 Conchology,' ix. (1887), pi. xix. fig. 6. 



f Tye, 'Quarterly Journal of Conchology,' i. (1878), p. 409. 



I Gibbons, 'Journal of Conchology,' ii. (1879), p. 134. 



§ Macdonald, ' Journal of the Proceedings of the Linnean Society ' : 

 Zoology, v. (1861), p. 209. 



|| Pease, 'American Journal of Conchology,' v. (1870), p. 81. 



