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CROSSOPTERYGII. 



Undina penicillata, Miinster. 



1834. Undina penicillata, G. von Miinster, Neues Jahrb. p. 539. 

 1842. Ccelacanthus striolaris, G. von Miinster, Neues Jahrb. p. 40. 



[Palaeontological Museum, Munich.] 

 1842. Ccelacanthus holder i, G. von Miinster, ibid. p. 40. [Ibid.] 

 1842. Ccelacanthus striolaris, G. von Miinster, Beitr. Petrefakt. pt. v. 



p. 57, pi. ii. figs. 1, 3, 5, 6, 8-10, 12, 14, 16. 

 1842. Ccelacanthus hohleri, G. von Miinster, ibid. p. 59, pi. ii. figs. 2, 4, 



7, 11, 13, 15, 17. 

 1844. Undina striolatus and U. hohleri, L. Agassiz, Poiss. Foss. vol. ii. 



pt. ii. p. 171. 

 18G3. Undina penicillata, A. Wagner, Abh. math.-phys. CI. k.-bay. 



Akad. Wiss. vol. ix. p. 696. 

 1869. Ccelacanthus penicillatus, R. von Willemoes-Suhm, Palaeonto- 



graphica, vol. xvii. p. 80, pi. x. figs. 2, 3, pi. xi. fig. 3. 

 1871. Ccelacanthus harlemensis, T. C. Winkler, Archives Mus. Teyler, 



vol.'iii. p. 101, pi. iv. [Teyler Museum, Haarlem.] 

 1881. Ccelacanthus harlemensis, B. Vetter, Mittheil. k. mineral.-geol. 



Mus. Dresden, pt. iv. p. 13, pi. ii. fig. 4. 

 1887. Undina penicillata, K. A. von Zittel, Handb. Palseont. vol. iii. 



p. 175, woodc. fig. 177. 



1887. Undina acutidens, K. A. von Zittel, ibid. p. 175, woodc. fig. 177b 

 (fig. of scales only). 



1888. Undina penicillata, 0. M. Reis, Palaeontographica, vol. xxxv. 

 pp. 30, 36, pi. ii. figs. 5, 6, 9, 10, pi. iv. figs. 3, 4. 



1888. Undina acutidens, O. M. Reis, ibid. pp. 10, 36, pi. i. figs. 2-6, 

 8-24. [Palaeontological Museum, Munich.] 



Type. Nearly complete individual ; Palaeontological Museum, 

 Munich. 



The type species, attaining a length of about 0-4. Trunk robust, 

 but elongated : head and opercular apparatus occupying somewhat 

 less than one quarter of the total length. Fin-rays slightly ex- 

 panded in the articulated distal half ; dorsal fins well developed, the 

 first consisting of about 10 relatively stout rays, the second and the 

 anal each comprising at least twice that number of more slender rays ; 

 principal caudal fin comprising about 18-20 stout rays above and 

 below. Jugular plates four times as long as broad, covered with 

 sparse elongated tubercles ; operculum, cheek-plates, and mandible 

 delicately tuberculated. Scales ornamented with numerous irre- 

 gularly and closely arranged, elongated tubercles. 



The occasional smooth appearance of the jugular, operculum, and 

 cheek-plates of this species is doubtless owing to post-mortem 

 accident before or during fossilization. The same remark probably 

 applies to the varying presence or absence of the larger teeth among 

 the smaller ones. 



