232 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



immediately above and those immediately below the oesophagus more or 

 less specialized ; eyes developed in the adult ; gill-openings 7, arranged 

 in a row along the sides of the "chest"; nostril on top of head just in 

 front of the eyes ; lips present, usually fringed ; dorsal fin more or less 

 deeply divided by a notch, the posterior part commonly continuous with the 

 anal around the tail ; intestines with a spiral valve ; eggs small. 



Key to the South American Genera of PETROMVzoNiDiE. 



a. Supraoral lamina median and undivided ; anus under the anterior part of the second dorsal ; 

 second dorsal fin distinct from the caudal. 



b. Lingual teeth distinct and conic ; supraoral lamina transversely extended, quadricuspid ; 

 infraoral crescent-like, sinuous or denticulate on the edge ; discal teeth numerous and 

 in divergent series. i. Gcotria. 



bb. Lingual teeth three, standing on the same base, pointed and curved, the median smallest ; 

 discal teeth in concentric series, the outer containing the largest teeth, about 24 on each 

 side. 2. Exoniegas. 



aa. Two lateral supraoral laminae entirely separate, triangular, each with three conic teeth ; infra- 

 oral lamina crescent-shaped, with about nine acute conical cusps ; discal teeth in somewhat 

 distant series, radiating from the center, those of a series more or less confluent ; lingual 

 teeth serrate, in two pairs ; anus under the posterior part of the second dorsal ; posterior 

 dorsal continuous with the caudal. 3. Caragola. 



I. GEOTRIA Gray. 



(Plate XXX.) 



> Geotria Gray, Proc. Zool. Soc. London, 1851, 238, pi. IV, fig. 3, and pi. 



V; id. List Spec. Fish. Brit. Mus. I, 142, pi. i, fig. 3 and pi. 2, 1851 

 [mtstralis). 



> Velasia Gray, Proc. Zool. Soc. London, 1851, 239, pi. IV, fig. 4; id. 



List Spec. Fish. Brit. Mus. I, 143, pi. i, fig. 4, 185 1 {chilensis). 

 = Velasia Gunther, Cat. Fish. Brit. Mus. V, 508, 1870; Gill, Proc. U. S. 



Nat. Mus. V, 524, 1882 [chileiisis). 

 Macyoplithalmia Plate, Sb. Ges. Naturf. Fr. Berlin, 1887, 137 [chilensis). 

 Type : Geotria australis Gray. 



Distribution : Temperate regions of the southern hemisphere. 

 Distinguished from Exomegas by having distinct lingual teeth. 

 Plate distinguishes between the three species of this genus as follows : 



a. Labial teeth numerous and close together. 



b. Outer hngual tooth very large, with 2 large and i median short point on a low base ; 

 two small inconspicuous inner lingual teeth. Supraoral plate plainly denticulate ; a small 

 gular sack in the ripe 9- Australia, New Zealand and South America. i, ckilensis.' 



