298 On the Skeleton of Nyctodactylns, with Restoration 



ceedingly thin they have been invariably flattened ont in fossilization; 

 the first phalange of the wing finger, the longest bone in the skeleton, 

 has a thickness at its middle, as crushed, of less than one and a half 

 millimeters. On account of this flattening, it is difficult to estimate 

 accurately the real width that the bones had in the living skeleton; 

 possibly they are represented in the drawing, for the most part, too 

 broadly. 



A brief resume of the more important osteological characters of this 

 pterodactyl may now be given as follows: 



Head long and slender, toothless; antorbital opening confluent with 

 the nares; atlas and axis partly or entirely coossified; seven true cervi- 

 cal vertebra present, without free ribs, and with non-nrticular ex- 

 apophyses.' Eighth vertebrae apparently ribless, much shorter than the 

 seventh, with the posterior zygapophyses much prolonged; ninth, tenth 

 and eleventh vertebra, that is, the second, third and fourth dorsals, co- 

 ossified, and each with stout coossified ribs, or much elongated diapoph- 

 yses, articulating with the sternum; fifth to ninth dorsals, inclusive, 

 short, stout, procoelous, with elongated diapophyses; tenth, and perhaps 

 also the ninth (which is partly concealed beneath the radius), coossified 

 Math the sacrum; sacrum composed of six firmly fused vertebra, all imited 

 with the ilium, and tapering much distally; caudal vertebrae amphi- 

 platyan, probably about twelve in numlier (the first one and the three 

 distal ones, only, so far discovered in the specimen). Ilium projecting 

 far in front of the sacrum, narrow: ischium (or conjoined ischium and 

 pubis) with a long, somewhat arcuated median symphysis, and with a 

 large obturator foramen; acetabulum imperforate, situated far dorsad; 

 prepubis (pubis?) band-like, with an anterior projection, U-shaped in 

 life. Sternum very broad and thin, evidently deeply concave above, 

 without keel, but with a stout presternal process ; with four costal articu- 

 lations on each side, and a median, flattened, xiphisternal process. 

 First three or four dorsal ribs stout, coossified with the vertebrae, and 

 articulating with the sternum; posterior ribs very slender, almost thread- 

 like, probably articulating in front with the extremities of the abdominal 

 ribs, single headed; abdominal ribs at least four in number on each side; 

 arranged very much as are the costal cartilages of the sixth to the tenth 

 ribs in man, but joined in front and attached to the xiphisternal process. 



2 Plienin.o-er, (Paleontographica, XLVIII, sa, 1901) objects to this term, and identi- 

 fies the processes with the parapophyses. Assuming that they are morphologically 

 identical with the real parapophyses, which is by no means proven, and is to me very 

 doubtful, their very different position and function necessitate a distinctive name, 

 for which I proposed that of exapophyses (Kans. Univ. Quarterly, 1896). 



