272 PALEONTOLOGY OF NEW YORK. 



Genus MIMULUS, Barrandk. 1879. 



PLATE Xlc , FIGS. 23-32. 



1878. Spiriftra{f), Miller and Dyer. JouriKil Cim-innati Soc. Nat. Hist., vol. i, p. 37, pi. ii, fig. 3. 



1879. Triplegia, Hall. Trans. Albany Institute, vol. x. Abstract, p. 16. 



1879. Mhiiulus, IJarrandb. Systeme Silui-ien du Centime de la Boh6me, vol. v, ]>. 109, pi. 1, fig-, iii ; 



pi. 9, tigs, iii, iv, vi. 

 1882. jfripZiis'/a, Hall. Eleventh Ann. Rept. State Geologist of Indiana, p. 298, pi. xxvii, tigs. 19-22. 

 1889. Streptui, Beechbr and Clarkes. Memoirs N.Y. State Mnsenm. 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. Barranue has given no clue to tlie interior characters 

 of tlie 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 pu'illus, 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 extt'rieure est coraplMement 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'an'-a 

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

 un deltidium, jusqu'au crochet. Celui-ci parait conserver un petit tron rond, 

 que nous observons sur un spt'-cimen non figure. 



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

 avec I'area est completement efface. 



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

 tement les caractrres, que nous venous 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- 



' ZrrTEL (Handbiu-h dei' Paheontologie, vol. i, j). 684) made it a sub-genus of Spiriper, .and CEiilbrt 

 (Fischer's Manuel de Coueliyliologie ; Br.achiopodes, \>. 1313) placed it with doubt un<ler the family Hhyn- 



CHoyKl.r.ID K. 



