new Species 0/ Semionotus. 179 



Semionutus curtulus, Costa, Paleont. del Regno di Napoli, pt. 1 (1850), 



p. 64, pi. vi. figs. 4, 5, pi. vii. fig. 6, pi. viii. fig. 2 ; pt. 3, p. 81, 



pi. xi. fig. 1 ; also Ittiol. Foss. Ital. I800, p. 25, pi. iii. fig. 1. — Lias, 



GifFoni, near Naples. 

 *Semionotus Pentlcmcli, Egerton, Proc. Geol. Soc. vol. iv. 1843, p. 183. 



— Lias, G-iffoni, near Naples. 

 ^Semionotus pustulifer, Egerton, loc. cit. — Lias, Gifibni, near Naples. 

 *Semionotus minutus, Egerton, loc. cit. \? = Notagogzis^ — Lias, Giffoni, 



near Naples. 

 ^Semio7iotus Manselii, Egerton, Figs, and Descrip. Brit. Org. Remains 



(Mem. Geol. Surv.), dec. xiii. pi. viii. (1872). — Kimmeridge Clay, 



Dorsetshire. 



Comparing the Broi'a fossil with each of the foregoing forms 

 it soon becomes evident that the fish is specifically distinct. 

 S. Bergeri obviously differs in the prominence of the serra- 

 tions on the scales, and the larger size of the fin-fulcra, 

 though agreeing well in general proportions. 8. Kapffi and 

 8. Brodiei are smaller species, and the former is considerably 

 less fusiform. 8. latus is likewise a much shorter and deeper 

 species ; and 8. striatus is distinguished by the character of 

 the superficial ornamentation of the head. 8. Nilssoni has 

 the scales of the flanks more vertically elongated, and is a 

 comparatively deep-bodied fish. 8. leptocephalus is very 

 similar to the Brora fossil in general outline, but the tail is 

 relatively smaller and the fin-rays apparently less robust. 

 8. curtulus^ 8. Pentlandi.^ and 8. pustuUfer must have been 

 all less elongated ; while 8. minutus^ if really referable to 

 the same genus, differs in the delicacy of the fin-rays and its 

 remarkably elongate shape. Lastly, 8. Manselii is readily 

 separated by its larger dimensions, the well-developed pelvic 

 fins, and the relatively greater depth of the trunk. 



It thus becomes necessary to propose a new name for the 

 species here described, and I would suggest that of 8. Joassi 

 as being most appropriate, in reference to the valuable re- 

 searches of the Rev. Dr. Joass upon the geology of the north- 

 eastern margin of the Highlands. 



EXPLANATION OF PLATE VII. 



Semmiotus Joassi, A. S. Woodw., Lower Oolite, Brora, Sutherland- 

 shire. 



JFtff. 1. Nearly complete fish ; nat. size. 



Fie/. 2. Premaxilla ; thrice nat. size. 



Fi(/. 3. Maxilla ; thrice nat. size. 



Fig. 4. Posterior branchiostegal ray ; twice nat. size. 



Fig. 5. Gular plate ; twice nat. size. 



Fig. 6. Postclavicular plate ; twice nat. size. 



Fig. 7. Caudal fin ; nat. size. 



Fig. 8. Scales of flank, inner aspect ; twice nat. size. 



Fig. 9. Ventral scales, inner aspect ; twice nat. .size. 



