552 
ADDENDA ET CORRIGENDA. 
41866-67. Three examples of the left mandibular tooth, the 
largest measuring 0*015 from the symphysial to the 
post-oral border ; Kimmeridge Clay, Weymouth. 
The symphysial, median, and posterior outer tritors 
are represented, hut the median is very narrow, and 
the anterior outer tritor is absent or not differen¬ 
tiated from the median. The beak is small; the oral 
margin is relatively short and faintly wavy, with a 
slight prominence at the posterior outer tritor ; and 
the post-oral margin is nearly parallel to the sym¬ 
physis. The oral face is much upturned. 
Purchased , 1869. 
P. 72. The following tooth, also from the Kimmeridge Clay of 
Weymouth, seems to represent an undetermined genus 
allied to Ischyodus. 
43284. Left mandibular tooth, 0*014 in length, much 
laterally compressed, and with an external thickening 
immediately below the oral border. This border is 
deeply sinuous, and the symphysis is very narrow. 
Two outer tritors and one beak-tritor occur, each 
being small, styliform, and laminated ; but there is 
no median tritor. Purchased , 1871. 
P. 118. To the second group of Ichthyodorulites add the follow¬ 
ing :—- 
Compsacanthus carinatus , J. W. Davis, Trans. Boy. Dublin Soc. 
[2] vol. i. (1883), p. 354, pi. xlvi. fig. 10.—Lower Car¬ 
boniferous Limestone; Armagh. [ Olim Enniskillen Coll.: 
see Introduction.] 
Tubulacanthus sulcatus , A. Eritsch, Eauna der Gaskohle, vol. ii. 
(1889), p. 113, pi. lxxxviii. fig. 14.—Lower Permian; 
Kounova, Bohemia. [Boyal Bohemian Museum.] 
Bvachiacanthus semiplanus, A. Eritsch, ibid. p. 113, pi. lxxxiii. 
fig. 10.—Ibid. [Ibid.] 
Platyacanthus ventricosus, A. Eritsch, ibid. p. 113, pi. lxxxvi. 
fig. 5.—Ibid. [Ibid.] 
P. 123. Some genera of the third division of Ichthyodorulites have 
recently been associated with the Myriacanthidas by O. 
Jaekel, and the miscellaneous and indefinable group thus 
formed is named Trachyacanthidae (Sitzungsb. Gfes. naturf. 
Freunde, Berlin, 1890, p. 130). 
