April II, 1889] 



NA TURE 



563 



actions (vol. clvii., 1867). Since that time Sphenodcm (of 

 which very few specimens were then known, and which 

 was even supposed to be nearly extinct) has been found 

 in abundance on various small islands in the Bay of 

 Plenty, and has come into the hands of many anatomists, 

 to the great benefit of reptilian morphology. An investi- 

 gation of the development of this type is, unfortunately, 

 still a desideratum, which, when supplied, cannot fail to 

 throw great light upon the phylogeny of the Reptilia. 



On the ground of its osteoiogical structure and of the 

 absence of copulatory organs, Sphetiodon was recognized 

 ')y Dr. GUnther as the type of a distinct order, the Rhyn- 

 hocephalia, a view in which he has been followed by 

 l^rof. Cope, who even goes further, and, very correctly as 

 we think, approxirnates them to the Plesiosaiiria and 

 Chclotiia. However, the authority which attaches to the 

 views of Prof. Huxley, who demurred to the ordinal 

 separation of the Rhyncliocephalia from the Lacertilia, 

 has deterred a great number of systematists from accept- 

 ing the order, and among these we find Dr. Credner still 

 terming Hatteria a Saurian. Now, if the Saurians are to 

 include the Rhynchocephalians, it seems unnecessary- to 

 divide the Reptiles into orders at all ; we may safely say 

 that, as far as our present knowledge goes, the difference 

 between the Rhynchocephalians and the Lacertilians is 

 ten times greater than that between the former and the 

 Plesiosaurians, or between Crocodilians and Dinosaurians, 

 and many times more so than between Lacertilia and 

 Ophidia. The two latter are accepted as orders by those 

 who refuse that rank to the Rhynchocephalia, but they 

 hardly deserve to be looked upon as more than sub-orders 

 in a group to be termed, in virtue of the law of priority, 

 the Sqiiaviata. The RhyncJiocephalia must be regarded 

 as the most generalized of all recent and, perhaps, of all 

 known Reptiles ; in many points they approach the 

 Stegocephalous Batrachians, and it is possible that the 

 common ancestors of the Chelonia, the Plesiosaiiria^ and 

 the Lacertilia would fall in this order. 



The following is Dr. Credner's definition of the new 

 genus PalcFohatteria : — 



Habitus^ that of a long-tailed lizard, 16 to 18 inches 

 long, with robust limbs. 



Vertebral colunm consisting of about six cervical, 

 twenty dorsal, three or four distinct sacral, and fifty to 

 fifty-five caudal vertebra:. Vertebral centra, solid amphi- 

 ■coelous sheaths which constrict but do not interrupt the 

 notochord. Neural arches united to the centra by suture. 

 Dorsal vertebrte with long anterior, caudal vertebras with 

 long posterior articular processes ; no transverse processes ; 

 spinous processes of dorsal vertebras elevated, with 

 rounded upper border, decreasing rapidly on the tail 

 to small tubercles, more and more posterior in posi- 

 tion, and finally entirely disappearing. Small wedge- 

 shaped intercentra between all pr;e-caudal and the 

 anterior caudal centra ; from the sixth caudal vertebra 

 they are modified into chevrons. All prae-sacral, sacral, 

 and the seven anterior caudal vertebrae with ribs. 

 Dorsal ribs long and curved ; cervicals straight ; last 

 dorsals short and feebly curved ; sacrals short and stout ; 

 caudals short, hooked. Proximal extremity of ribs ex- 

 panded, not divided into capitulum and tuberculum. 



Skull pointed and compressed ; orbits large and 

 circular, with sclerotic ring ; nostrils small, anterior ; 

 idtero-temporal fossae comparatively small. Dentition 

 acrodont, the teeth acute and conical, slightly curved 

 backwards at the extremity ; a thin coating of dentine, 

 which on the inner side of the basal third shows slight 

 ^nooves. Prae-maxillaries distinct, each with three or four 

 slender somewhat more strongly-curved teeth. Maxillary 

 extending high up, armed with sixteen to eighteen teeth, 

 of which the sixth and seventh are enlarged. Nasals 

 nearly as long as the frontals. A large lachrymal be- 

 tween prte-frontal and maxillary. Jugal bordering the 

 orbit inferiorly, bifurcating posteriorly into an ascend- 



ing and a horizontal branch ; the former forms with 

 the post-orbital and the post-frontal a vertical post-orbital 

 bar, the latter a horizontal bar with the quadrate.^ Squa- 

 mosal curved, fan-shaped, in contact anteriorly with the 

 post-orbital, posteriorly with the horizontal branch of the 

 jugal and with the quadrate. Basisphenoid a trapezoid 

 plate with short lateral processes, with two small per- 

 forations near its anterior extremity, which tapers to 

 the pointed prae-sphenoid. Vomer with hatchet-shaped 

 groups of small teeth. Palatines with a series of teeth, 

 parallel to the maxillaries, on the outer border. Mandi- 

 bular ramus slender, straight, without coronoid process, 

 formed of articular, angular, supra-angular, dentary, and 

 probably also opercular and splenial. 



Pectoral arch consisting of a long styliform episternum 

 [interclavicle], which expands anteriorly into a small 

 rhombic plate ; two elbow-bent clavicles, overlapping the 

 inner side of the episternal expansion ; two crescentic 

 scapulae, truncate at each end and strongly thickened on 

 the posterior border ; and two non-perforated roundish 

 coracoids. 



Pelvis consisting of three paired elements, viz. a short 

 massive ilium, with crest-like upper expansion and two 

 diverging lower processes ; a triangular posteriorly pro- 

 duced ischium ; and a transversely oval, plate-shaped 

 pubis with obturator foramen. 



Limbs strong and stout, the posterior a little longer 

 than the anterior. Distal extremity of humerus much 

 expanded, with ectepicondylar foramen. Carpus with 

 eight or nine ossified elements ; tarsus formed of cal- 

 caneum, astragalus, and five tarsalia ; five metacarpals 

 and five metatarsals ; five digits to both limbs, the first 

 with two, the second with three, the third with four, the 

 fourth with five, and the fifth with three phalanges, of 

 which the distal is a sharp curved claw. 



Abdominal ribs probably present, and formed of 

 numerous small filiform bones. 



An armour of small oat-seedshaped scales, forming 

 posteriorly diverging series, restricted to the ventral 

 region between both pairs of limbs. 



Among the most salient features in the structure of the 

 new Reptile, as compared with other Rhynchocephalians, 

 are the pelvis and the tarsus. The crest-like expansion of 

 the costal border of the ilium and the bifurcation of its 

 acetabular extremity, are, to a certain extent, Crocodilian 

 or Dinosaurian, whilst the pubis and ischium appear to 

 us to bear the greatest resemblance to the same in Plesio- 

 saurians. It is also in the latter group that we have to 

 look for so primitive and Batrachian-like a tarsus ; for the 

 tarsus of Palccohatteria affords an exact repetition of that 

 of the likewise Pernio- Carboniferous Plesiosaurian Stereo- 

 sternum, which, on the ground of its five distal tarsalia 

 has been made the type of an order, Proi^anosauria, by 

 Dr. Baur. The close similarity of the dentition of Palcso- 

 hatteria and that of certain contemporary Stegocepha- 

 lians, especially Dendrerpeton and Hylonomus, is highly 

 suggestive of relationship, and we are not surprised to hear 

 from Dr. Credner himself of his having at first felt uncer- 

 tain as to the class to which the fossil should be referred. 

 Although unquestionably related to Sphenodon, Palceo- 

 hattcria has, we venture to think, yet hardly a claim to 

 enter the Hatteriidce, and it would have been better had 

 the author established for it a new family. The archaic 

 condition of the humerus with both ent- and ect-epicon- 

 dylar foramens, the presence of uncinate processes to 

 the ribs, the absence of a ventral armour, the presence 

 of a coronoid process in the mandible, and the share 

 taken by the maxillary in the formation of the border of 

 the orbit, a character common to the Chelonians and 

 Plesiosaurians and certain Lizards, but not found in the 

 Stegocephalians, the Ichthyosaurians, the Crocodilians, 

 nor, we believe, in the other Rhynchocephalians, are 



' Wh.-it Dr. CreJner calls "quadrate" is in re.-ility quadrate -1- quadrato- 

 jugal. 



