Cope.] ^^^ [i^ov. 18, 



A number of consecutive vertebraa are preserved, wliich. represent the 

 posterior portion of the caudal series. One of these is fortunately the 

 very extremity, and they demonstrate the tail to have been vertebrated 

 or heterocercal, after the manner of Amia. On the anterior series of 

 three the lateral grooves have disapijeared from the centra ; the neural 

 canal is very small, and the spines are very massive and curved back- 

 wards, but much less than in the more posterior parts of the column ; 

 they are flattened, wider than deep, and in close contact with each other. 

 The anterior of the three, on the other hand, presents a narrowed edge 

 forwards. The hsemapophyses are thin, and suturally united by a flat 

 gomphosis. The terminal series embraces six vertebrsB, which have a 

 minute or obsolete neural canal, but haemal canal distinct, but apparently 

 interrupted. The haemal arches are united to the centra by a rather 

 smooth suture. 



The general direction of these vertebrae forms a light upward curve. 

 The haemal spines are flat and laminar, and their margins in contact ; 

 they decrease in width and length to the end of the series. The neural 

 spine lies obliquely backwards, and has a narrowed anterior ridge, but 

 stout shaft. 



The anterior haemal spine in place exhibits a subglobular base, like 

 an articulation, and its shaft is wider than those posterior to it. A sub- 

 triangular flat bone, with neck and subglobular extremity, applies very 

 well to a concavity between the anterior pair of pleurapophyses, but does 

 not in that position preserve contact with the anterior margin of the 

 second spine. One margin of the enigmatical bone is thin and divergent ; 

 the other expanded laterally and straight. The latter gives off a trans- 

 verse prominence like half a globular knob before reaching the extremity. 

 Just within the latter are two large foramina, which are connected with 

 the extremity by a groove on each side, which meet in a notch where the 

 thin edge passes into the knob. 



Both sides of the neural and haemal spines are concealed in this species 

 and in the S. prognathus by numerous parallel osseous rods, which are 

 somewhat angulate in section. They lie along the centra of the anterior 

 series of caudal vertebrae, but are not to be found on vertebrae of any 

 other part of the column. jSTumerous loose and fragmentary rods of the 

 same character accompany the loose and attached caudal vertebrae, and 

 all of them, according to Prof. Mudge, belong to the "posterior swim- 

 ming organ" of this animal. There is also a collection of these rods 

 from the anterior region of the body, which Prof. Mudge thought occu- 

 pied the position of an anterior limb. They do not any of them present 

 a segmentation such as would be exhibited by the cartilaginous radii of 

 caudal and pectoral fins, and their nature might have remained doubtful 

 but for the explanation furnished by the anterior compound ray or spine 

 of the posterior, probably caudal fin. This ray, as in the case of the 

 pectoral spine and first anal rays of some existing Siluroid and Loricariid 

 fishes, is composed of a number of parallel rods closely united. These 



