WOOD, PHYLOGENY OF CERTAIN CERITHIIDM 31 



show such strong evidence of relationship with European forms that we 

 must assume some at present unexplained means of intercommunication 

 between species of the east and west shores of the Atlantic. This connec- 

 tion probably existed at some earlier geological period, since Miocenic 

 species show the same similarity to European forms as do the recent 

 species. 



Cerithium caudatum Sozverby 



1855. Cerithium caudatum. Sowebby, Thesaurus Conch., II, 856, pi. 179, figs. 

 71, 72. 



1866. Cerithium caudatum Reeve, Conch. Iconica, XV, No. 16. 



1898. Cerithium caudatum Kobelt, Syst. Conch.-Cahlnet von Martini u. Chem- 

 nitz. Bd. I, Abth. 26, 112, pi. 22, fig. 4. 



Measurements: Length, 31.5 mm.; greatest diameter, 14.2 mm.; apical 

 angle, 41°, changing to 29° on the last three volutions; sutural angle, 75°. 



Color: Golden brown. Lighter in color at the apex and on the varices. 

 Margin of the outer lip white streaked with black. 



The apex of the shell is much corroded. The ^^oungest volution to 

 show the surface is 2 mm. in diameter, and has the ornamentation char- 

 acteristic of this group of ribs and two strong spirals. At this stage 

 intercalated spirals are already introduced between the two primary ones, 

 and spirals of at least two orders are present on the shoulder and on the 

 lower slope of the whorl. The surface ornamentation remains of the 

 same type, with the introduction of more spirals, until tlie eighth volu- 

 tion, after which the ribs become discontinuous and the stronger spirals 

 break up into nodes. On this volution there is a sub-sutural row of 

 nodes, and each of the two primary spirals also forms a row of nodes. 

 The outline of the volution is an obtuse angle, with a sloping or concave 

 upper surface and vertical sides. On the ninth volution preserved the 

 finest of the spirals have become obsolete, and between the rows of nodes 

 the spirals are comparatively few and coarse, with narrow interspaces. 

 On the body volution the nodes of the lower primary' spiral become very 

 small, no larger than those of the secondary spirals. This volution has 

 one row of strong nodes — those of the first primarv spiral — a row of sub- 

 sutural nodes somewhat smaller and three rows of fine nodose spirals on 

 the lower slope of the whorl. The intermediate spirals are crenulated, 

 but not distinctlv nodose. 



The aperture is oval and the callus of the inner lip is thin, with a well- 

 developed posterior tooth. The outer lip is distinctly flaring and finelv 

 crenulated along its outer margin. The anterior canal is short and 

 widely open. 



