92 MEMOIRS OF THE QUEENSLAND MUSEUM. 



vii. Heterodontid^ : — - 

 </' . Ramal symphyses long ; supraorbital ridges gradually decreasing in height posteriorly 



21. Heterodontus. 

 a-. Ramal symphyses short ; svipraorbital ridges terminating abruptly behind 22. Gyropleurodus. 



viii. Narcacionid^ : — 

 (7^ Tail very short, with two dorsal fins ; spiracles close behind the eye, fringed . . 23. Hypno3. 



ix. Pbisteid^ : — Monotypic, v. supra. 

 X. Rhinobatid^ : — 

 «\ Rhamphobatince : — First dorsal fin originating above base of ventrals. 



6^ Snout short, broad, obtuse ; dental surface of jaws deeply undulovis . . 25. Rhamphobatis. 

 6". Snout narrow, produced, acute ; dental surface of jaws feebly vmdulous 26. Rhynchobatus, 

 a-. Rhinobatince : — First dorsal fin inserted well behind the ventraLs. 



c^ Nasal valves not confluent . . . . . . . . . . . . 27. Rhinobatus. 



xi. Rajid^ : — 

 qI. Ventral fins deeply notched ; dorsal fins far back, near tip of tail .. .. .. 28. Raja. 



xii. DASYBATID.E : — 



•a^. Disk not or not much wider than long, the outer angles rounded or nearlj' so. 



l)^. Urolophinoe : — Tail short, stout, muscular, terminating in a well-developed rayed caudal fin. 



29. Urolophus. 

 b'-. Dasybatince : — Tail moderate or long, without dorsal or caudal fin. 

 c^. Caudal spine developed. 



d^. Tail moderate, interiorly with a deep cutaneous fold which extends to its tip 



30. TiENIURA, 



e^. Dental surface of upper jaw angular ; tail inferiorly with a deep cutaneous fold, which 

 is proximal in position, leaving a long free tip .. .. 31. Hypolophus. 



e^. Dental surface of jaws straight or undulous. 

 /^. Tail moderate, with a low cutaneous fold on the upper or lower border, or on both 



32. DASYBATtrS. 



/-. Tail very long and slender, without folds . . . . . . . . 33. Himantura. 



C-. Tail long, spineless, foldless ; back covered with osseous tubercles intermixed with spini- 

 gerous bucklers . . . . . . . . . . . . 34. Urogymnus. 



«-. Pleroplateince : — Disk much wider than long, the outer angles pointed ; tail short, slender, rat- 

 like, the dorsal fin and caudal spine, when present, vestigial 35. Pteroplatea. 



xiii. Myliobatid^ : — 

 fl^. Myliobatince : — Rostral lobe simple, median. 



fti. Teeth in several series, middle widest . . . . . . . . . , . . 36. Myliobatis. 



b^. Teeth in a single series, very wide . . . . . . . . . . . . 37. Aetobatus. 



o'-. Rhinopterince : — Rostral lobe paired, lateral ; teeth in several series, middle \isually widest 



38. Rkenoptera. 

 xiv. Mobulid^ : — 

 a^ Mobulince : — Mouth inferior. 



b^. Teeth in the upper jaw only . . . . . . . . . . . . . . Ceratoptera.* 



b^. Teeth in both jaws . . . . . . . . . . . . . . . . 39. Mobula. 



a^. Mantince : — Mouth anterior. 



c^. Teeth in the lower jaw only. . . . . . . . . . . . . . , Manta.* 



Note : — None of the three genera to which an asterisk is attached has as yet been recorded 

 from our coast, but Hypoprion has been included, both because the Indo-Malayan H. macloti has 

 lieen taken in Port Jackson, but more especially to demonstrate the dental differences which separate 

 it from my genus Rhizoprion. Manta too has been Icnown for many years from Port Jackson ; there- 

 fore in view of the wide tropical distribution of the mobuloid rays, and the difficulty of obtaining 

 specimens owing to their huge bulk, it has been thought advisable to publish the above key to the 

 genera, in order to facilitate the identification of such examples as may from time to time be 

 captured. 



