EASTMAN: CARBONIFEROUS FISHES FROM THE CENTRAL WKST. 191 



The solitary known and probably immature example of this species is 

 shown of twice the natural size in Plate 5, Fig. 49. The head is poorly pre- 

 served, and the extremities of nearly all the fins are either broken away or 

 obscured by matrix. Nevertheless sufficient characters remain for the recoa- 

 nition of this as a distinct species of Elonichthys, its chief peculiarity consist- 

 ing in the remarkable development of all the fins. The pectorals are fully 

 one fourth as long as the entire body, and the anal has a more extended base- 

 line than in any other species of the genus. The dorsal appears to have been 

 high and acuminate, but is largely concealed by matrix. The caudal is also 

 unfavorably exposed, and flexed out parallel with the main axis, but it is plain 

 that the upper lobe was much prolonged, and covered with very large, striated 

 ridge-scales. The dorsal fin-rays appear to have been widely jointed ; the 

 articulations of the other fins are not clearly discernible. The dermal rays of 

 the anal and lower lobe of the caudal are directly supported by the enlarged 

 haemal spines, which are firmly united with their arches. The squamatiou is 

 nowhere well preserved, but is best indicated in the anterior part of the trunk. 

 The cranial structure does not admit of particular description. 



Elonichthys disjunctus, sp. nov. 



(Plate 3, Fig. 31.) 



Type. — Distorted individual ; Yale Museum. 



A species of about the same size as E. peltigerus and E. hypsilepis, and 

 resembling them in general form and ornamentation, but differing in the 

 position of the anal and structure of the paired fins. The latter are relatively 

 shorter in the present species, and have fewer rays. The dorsal and anal are 

 of about ec[ual size, triangular and acuminate, and each with 25 or more rays. 

 The anal is inserted opposite the middle of the dorsal, and its base-line ter- 

 minates at a distance in advance of the caudal at least as great as the depth of 

 the caudal pedicle. Caudal fin deeply forked and very finely divided ; fulcra 

 minute. 



Several examples of this species are preserved in the Yale Museum, the 

 smallest having a length of only 2.5 cm., and the largest upwards of 11 cm. 

 While exhibiting the same proportions as E. peltigerus and E. hypsilepis, it 

 differs in the less remote position of the anal fin. One specimen in the collec- 

 tion shows very perfectly the two series of piercing teeth, and about 14 bran- 

 chiostegal rays. The original of Plate 3, Figure 31, which is selected as the 

 type, has the body flexed in such wise as to present the ventral aspect of the 

 head and greater portion of the trunk, while the region behind the anal fin is 

 seen from the right-hand side. The caudal is very well shown ; the anal, on 

 the other hand, is somewhat distorted, and the dorsal and paired fins are 

 wanting. 



Formation and Locality. — Coal Measures; Mazon Creek, Illinois. 



