GEOLOGICAL SURVEY IN SILURIAN ROCKS OF SOUTH OF SCOTLAND. 833 



Description. — This is a larger species than the former, some of the examples in the 

 collection attaining a length of six inches. In general form it is identical with L. 

 horrida, but the maimer in which that form may be altered by distortion is well seen 

 in the examples figured in PL III. figs. 7 and 8, and PI. IV. fig. 12. My idea of the 

 undistorted form is given in the accompanying restored outline. 



The small spines are extremely minute, the larger ones (PL III. figs. 10-12) are 

 very similar to those of the preceding species, though not quite so trumpet-shaped ; they 



Fig. 1. — Restored outline of Lanarkia spinosa in the position in which it occurs as a fossil, namely, 

 vertically compressed in front, but the tail twisted round so as to appear in profile. 



are also hollow internally and minutely striated externally. The manner in which they 

 are interspersed among the smaller ones is shown in fig. 9 of this plate and in fig. 2 of 

 Plate IV. 



Position and Localities. — From the Downtonian Beds of Seggholm, Birkenhead 

 Burn, and Monk's Burn. 



Lanarkia spinulosa, Traquair. 

 Plate IV. figs. 3-5. 



1898. Lanarkia spinulosa, Traq., in Director-General's Summary of Progress for 1897, p. 73. 



Specific Character. — All the dermal spines minute, and without admixture of 

 larger ones. 



