4. GEOTRIA. O09 



Icaf-lilv-e frinf^es, as is the romairKlor of the margins of the disk. 

 Suctorial disk siil)triangular with the lateral lobes very broad. First 

 and second dorsal fins rather widely separated from each other. 

 Coloration uniform. 

 South Australia. 



a. Type of the species, 20 inches long. Iiik;iipinki River. Pre- 

 sented by 11. A. Pain, Esq. 



I recollect having seen a second and still larger specimen of this 

 Lamprey in the collection formerly at Fort Pitt, and now at Netlcy 

 Hospital. 



The use of the extraordinary sac at the throat is not known ; the 

 cavity is in the subcutaneous cellular tissue, and does not communi- 

 cate with the buccal or branchial cavities. It is probably absent in 

 younger individuals. 



PhiHppi (Wiegm. Arch. 1857, p. 266) has described a Lamprey 

 from Chile under the name of J'elasiu chilensis ; the example was 

 provided with the sac at the throat, and the description agrees with 

 Geotria australis ; so that wo must assume either that this latter 

 species occurs not only in Australia, but also in Chile, or that 

 Velasia chiJensis at a certain stage of development is provided with 

 a gular sac. If the latter be the case, the specific distinctness of 

 the two fishes would be questionable. The form of the mouth of 

 the example seen by Philippi, and figured in Wiegm. Arch. 1863, 

 taf. 10. fig. a, is exactly intermediate between that of the mouth of 

 the types of Geotria australis and VeJasia chilensis. 



2. Geotria chilensis. 

 Velasia chilensis, Grai/, I. c. p. 143, tab. 1. fig. 4. 



Skin on the throat not dilated. The outer lobes of the maxillary 

 dental lamina are broad with a sharp convex edge, the inner narrow 

 and pointed. Mandibulary lamina crescent-shaped, with numerous 

 obtuse points. Suctorial teeth in numerous series, so close together 

 that the teeth have the appearance of imbricate scales. A series of 

 larger, broad, scale-like teeth round the mandibulary lamina. Suc- 

 torial disk not dilated, circular. First and second dorsal fins widely 

 separate from each other. Sides and abdomen silvery ; back 

 greenish. 



Chile ; Swan Eiver ; New Zealand. 



a. Type of the species. Chile. 



b. Twenty-one inches long. Swan River. Purchased of Mr. Stevens. 

 c-f. Twenty-two inches long. New Zealand. Presented by W. 



Colenso, Esq. 



Prof. Kner (Novara, Fisch. p. 421) describes an Ammocoetes from 

 Auckland ; it is perhaps the young state of this .species. 



