434 THE PLAGIOSTOMIA. 



pectoral with the rostral fins, as may be probable, this species will have to be 

 placed in the genus Pteromylaeus. 

 Australia; New Zealand. 



Myliobatis rhombus. 



Myliobatis rhombus Basilewsky, 1855, Nouv. m£m., 10, p. 250. 



" Discus rhomboideus, subtus albescens, supra fuscus, pinnis pectoralibus 

 carnosis, valde dilatatis antrorsus in apicein acuminatum prominentem con- 

 junctis circumductus. Pinna dorsalis nulla; subcaudales duae, carnosae, latae, 

 discum postrorsum terminantes. Caput truncatum cum pectore dilatato 

 sursum prominens, et pinnis pectoralibus circumductum. Os subtus apertum, 

 transversum, magna maxilla inferiore hominis labii adinstar formata. Utraque 

 maxilla dentibus tetragonis, planis, latis, lapideis, invicem stricte imbricatis 

 obducta. Branchiarum aperturae ante os positae. Cauda disci longitudinae, 

 attenuata, filiformis, aspera, tuberculis acutis obtecta. Latitudo disci 1 pes 

 7 pollices. Longit. ejus excepta cauda 1 pes 8 poll, caudae 1 pes et 6 poll. 

 Habitat in Mare orientali et meridiano. Pekinum rarissime apportatur." 



Basilewsky 's description does not supply details enough for a proper deter- 

 mination of this species. 



Aetomylaeus. 



Aetomylaeus Garman,' 1908, Bull. M. C. Z., 51, p. 252. 



The typical species of this genus was described by Gray, 1S34, under the 

 name Myliobatis maculatus. In the form of head and disk all the members of 

 this genus resemble the species of Myliobatis; they are distinguished by the 

 rostral fins, which are not continuous with the pectorals at the side of the head, 

 but are situated at a lower level, and by the absence of a caudal spine. The 

 dentition consists of three lateral rows of quite narrow teeth at each side of a 

 median row of broad ones. 



Origin of dorsal behind ends of bases of ventrals 



back armed in the middle with small spines or tubercles 

 disk less than twice as broad as long 



brown-edged ocelli on hind part of disk . maculatus (page 435) 

 Origin of dorsal opposite ends of ventral bases 

 back smooth 



disk less than twice as broad as long- 

 green brown-edged ocelli on hind part of disk milvus (page 435) 



