Serpulorbis.] GASTROPODA. 259 



eggs are often attached to the shell itself. The embryos are furnished 

 with a spiral shell, and the young are often perforating. 



Fossil. Secondary and Tertiary. 



The Vermetidce are exceedingly irregular in growth, sculpture, and 

 colouring, often reproducing the surface upon which they are fixed. 

 There is a great resemblance of some of the forms to Annelids (Ser- 

 pulidce), from which they may be distinguished by the spiral nuclear 

 shell and interior septa of the tube. The tube of the Annelids is com- 

 posed of 2 calcareous layers ; that of Vcnuctidcp- of 3. 



KEY TO GENERA. 



A. Shell-tube with a longitudinal fissure, simple or formed by a 



series of perforations . . . . . . . . SrLiQUARlA. 



B. Shell-tube without longitudinal fissure or perforations. 



a. Operculum present. 



b. Operculum concave, with plain margin . . . . SIPHONIUM. 



bb. Operculum slightly concave, with horny bristles . . STEPHOPOMA. 

 aa. No operculum. Shell-tube with more or less distinct 



longitudinal lirse, sometimes decussated . . . . SERPULORBIS. 



Genus 1. SERPULORBIS, Sasso, 1827. 



Serpulorbis, Sasso, in " Giornale Ligurico," Genua, 1827, 482. Type : S. poly- 

 phragma, Sasso. Thylacodes, Guettard, 1774. Serpulus, Montfort, 1810 ; 

 not Serpula, Linn:, 1758. Linientina, Risso, 1826. Cellular ia, Schmidt, 

 1833. Cladopoda, Gray, 1840. Hatina, Gray, 1842. Serpuloides, Gray, 

 1850. Tetranemia, Morch, 1859. 



Shell adherent, frequently solitary, tubular, irregularly twisted, 

 with 3 to 5 longitudinal nodulous Iira3 ; aperture rounded, without 

 internal longitudinal plications, but frequently partitioned perpendi- 

 cularly to the axis. No operculum, or minute when present. 



Guettard established his genus chiefly on account of the internal 

 septa, the presence of which in his genus Campulotus was unknown to 

 him. 



KEY TO SPECIES. 



a. Shell with distinct moniliforrn longitudinal ribs and transverse 



growth-lines; no internal septa. . .. .. .. sipho. 



b. Shell sometimes with longitudinal strife and rugose growth-marks ; 



internal septa present . . . . . . . . . . zelandicus. 



1. Serpulorbis sipho, Lamarck, 1818. Plate 40, fig. 9. 



Vermetus sipho, Lamk., A.s.V., v, 626. Serpulus sipho, Hedley, P.L.S. 

 N.S.W., 1902, 602. Vermetus arenarius, Lamk. : Q. & G., Voy. Astrol., 

 iii, 289, pi. 67, f. 8-10 ; not of Lamarck. F. dentiferus, Lamk. : Q. & G., 

 f.c., 291, pi. 67, f. 27, 28 ; not of Lamarck. F. novoe-hollandice, Rousseau, 

 in Chenu, Illustr. Conch., 1847, pi. 1, f. 4a ; Man. Conch. (1), viii, 179, 

 pi. 53, f. 64. Cladopoda monilifera, Mutton, C. Tert. M., 13 ; Plioc. M., 

 66, pi. 8, f. 70. Thylacodes sulcntus, Tate and May, P.L.S. N.S/W., 

 1901, 377 ; not of Lamarck. Vermiculnria novce-hollandice, Rouss., 

 Index, 76. 



Shell large, vermiform, subsolitary or agglomerated, irregularly 

 twisted, brownish. Sculpture consisting of rugose growth - stride, 



9* 



