272 PALEONTOLOGY OF NEW YORK. 



Genus MIMULUS, Bareande. 1879. 



PLATE XEC , PIGS. 23-32. 



1878. S'pirifera {?), Miller and Dyeb. Joarnal Cincinnati Soc. Nat. Hist., vol. i, p. 37, pi. ii, fig-. 3. 



1879. Trijilesia, Hall. Ti'ans. Albany Institute, vol. x. Abstract, p. 16. 



1879. Mimulus, Bareande. Systfirae Silurien du Centre de la BohSme, vol. v, p. 109, p\. 1, fig. iii ; 



pi. 9, fiys. iii, iv, vi. 

 1882. Tr'qMna, Hall. Eleventh Ann. Rept. State Geologist of Indiana, p. 298, pi. xxvii, figs. 19-22. 

 1889. Streptis, Bebchbr and Clarke. Memoirs N.Y. State Museum, vol. i. No. i, p. 30, pi. iii, figs. 9, 10. 



The affinities of this peculiar group of fossils have not hitherto been cor- 

 rectly understood. M. Barrande has given no clue to the interior characters 

 of the shells, and as the genus has been recognized only in the Bohemian basin 

 it has not been closely studied by other authors.* After a careful comparison 

 of M. Barrande' s figures of the Bohemian species with the fossil known as 

 Triplesia puHllus, Hall, or Spirifera Waldronensis, Miller and Dyer, from the Niagara 

 fauna of Indiana, there remains little doubt of their being congeneric forms. 



The diagnosis of the genus, given by M. Barrande, is in the following 

 terms : 



" Cette forme exterieure est completement inverse de celle de Spirifer, en ce 

 que le bourrelet, bien marque, se trouve sur la valve ventrale, tandisque le sinus 

 correspondant se montre sur la valve dorsale. 



" La charniere est droite, mais n'occupe pas toute la largeur du fossile. L'area 

 bien developpee presente sous le crochet une ouverture triangulaire, fermee par 

 un deltidiuin, jusqu'au crochet. Celui-ci parait conserver un petit trou rond, 

 que nous observons sur un specimen non figure. 



" II est rare de pouvoir observer le deltidium, parceque la trace de la soudre 

 avec I'area est complrtement eftaci''. 



" Les 2 especes typiques, Mim. perversus et Mim. moera, PL 9, presentent exac- 

 tement les caracteres, que nous venons d'exposer." 



The exterior form of these shells is subtrihedral like Triplegia, and is 

 subject to some variation, for of the three species described by M. Barrande, 

 two, M. perversus and M. moera, have the strong median fold on the pedicle- 



* ZiTTEL (Handbucli der Palseontologie, vol. i, p. 684) made it a sub-genus of Spirifer, and CEhlebt 

 (Fischer's Manuel de Conchyliologie ; Bracliiopodes, p. 1313) placed it witli doubt under the family SHYif- 



CHONELLIDM. 



