



1884.1 *** [Cope. 



present character by a process of degeneration. "The origin of the Verte- 

 brata is as yet entirely unknown, Kowalevsky deriving thern from the 

 Tunicata, and Semper from the Annelida. 



Aves Mammalia 



Keptilia 



Hyopomata Batrachia 



I \ 



Selachii Ichthyotomi Dipnoi 



Holocephali 



Marsipobranchi 

 Leptocardi 



EXPLANATION OF PLATE. 



Fig. 1. Clepsydrops leptocephalus Cope, right quadrate bone (Q) with 

 condyle and zygomatic process (z) from the right, or external side. Pt, 

 pterygoid bone of same side displaced so as to be in plane of quadrate, 

 and to be seen from inferior side. One-half natural size. 



Fig. 2. Columella auris of the individual of Clepsydrops leptocephalus 

 represented in fig. 1 ; internal side. Fig. 2a external side ; 2b proximal 

 extremity ; 2c distal extremity ; s, head of stapes ; Ecol. epicolumella ; 

 d, distal articular surface, especially represented in fig. 2c. All figures 

 are half natural size, excepting 2c, which is natural size. 



Fig. 3. Left half scapular arch of a Pelycosaurian, less clavicle and 

 episternum, one-half natural size, sc, scapula ; el, facet for clavicle : 

 cor, coracoid ; ec, epicoracoid ; s, open suture between coracoid and 

 epicoracoid, indicating the immaturity of the animal. 



Fig. 4. Dorsal vertebra of a species of Embolophorus, one-half natural 

 size; right, side; a, from front; b, from below; ic, intercentrum; ca, 

 capitular rib articulation. 



Fig. 5. Astragalus of individual figured in fig. 4, one-half natural cize ; 

 from below, ca, ca, facets for calcaneum ; na, do. for navicular ; tib, 2, 

 do. for bone of spur, or os tibiale. 5a, same bone from external or cal- 

 caneal border ; /, fibular facet, ob, same bone, proximal or fibular ex- 

 tremity. 



Fig. 6. Left posterior foot of Clepsydrops natalis Cope, superior side, 

 and 6a, inferior (plantar) side, two-thirds natural size, as, astragalus ; 

 ca, calcaneum ; na, navicular bone ; cu, cuboid ; euc, mo and ecc, en- 

 tocuneiform, mesocunei'form and ectocunei'form bones, respectively. I, II, 

 III, "IV, V, metatarsals. Tib 1', Probable tibial facet. In this specimen 

 the calcaneum is displaced ; being turned backwards, so as to present its 

 two astragalar facets (aaf) anteriorly. 



Printed November 20, 1884. 



