88 PATAGONIAN EXPEDITIONS: PALAEONTOLOGY. 



4 



.PELTEPHILID^E Ameghino. 

 PELTEPHILUS Ameghino. 



(Plate XVI.) 



Peltephilns Amegh. ; Enumeration sistematica, etc., 1887, p. 25. 

 Cochlops Amegh., in part; Contribution al Conoc. de los Mam. Fos. de 



la Rep. Arg., 1889, p. 792. 



Gephyranodus Amegh.; Rev. Argent, de Hist. Nat, T. I, 1891, p. 119. 

 ? Anantiosodon Amegh., Ibid., p. 327. 



This extraordinary genus is one of the most curious of Santa Cruz 

 mammals and, although containing several species, is comparatively rare 

 among the fossils. Almost all parts of the skeleton are now well 

 known and show that these animals were unmistakable armadillos and yet, 

 in many respects, extremely aberrant. 



Exoskeleton. Not the least peculiarity of the genus is the remarkable 

 cephalic shield (Plate XVI, figs. 2, 6, 7), which is utterly unlike that of any 

 other known armadillo. In P. ferox and, doubtless, in the other species 

 also, the shield consists of nineteen or twenty-one large and heavy plates 

 of bone, arranged to form a definite pattern. In the median line and ex- 

 tending from the occipital crest to the anterior edge of the orbit, are three 

 symmetrical, unpaired plates, of which the posterior is the largest of the 

 entire shield and has a somewhat irregularly hexagonal shape. In its 

 shape and proportions, this posterior median plate differs considerably in 

 the different species, but appears to be constant in each species. The 

 second median plate is longer and much narrower and the anterior one 

 much smaller. On each side of the median series are seven plates of 

 varying sizes and shapes, but all polygonal except the postorbital, which 

 curves downward almost to the zygomatic arch and ends in a blunt point. 

 Most remarkable of all is the pair of plates which are situated on the 

 nasals and maxillaries and have subquadrate bases, rising into high, sharp- 

 pointed, slightly incurved and recurved horns. Ameghino believes ('94(7, 

 177) that a second pair of horn-like scutes is placed on the nasals in front 

 of the principal pair, but I have not been able to satisfy myself entirely 

 that this is true. All the plates of the head shield have a very rugose 

 surface ; the markings appear to be constant for each species. 



As yet, no considerable part of the carapace has been found, but great 

 numbers of separate scutes have been collected, all of which are extremely 



