466 Miscellaneous. 



This Peruvian lish however is interesting from its showing that there 

 exist fishes there which live principally upon infusorial mud. Whe- 

 ther this occurs upon an extensive scale and also in the case of the 

 salt-water fish of that country must be left to further inquiry. 



In the small sample of the contents of the stomach forwarded, the 

 following species have been determined : — 



POLYGASTRICA 27. 



Amphora gracilis. Navicula lineolata. 



Cocconeis fasciata. Scalprum. 



Placentula. Pinnularia afifinis. 



Cocconema Leptoceros. borealis. 



Lunula. peregrina. 



Coscinodiscus radiolatus } viridis. 



Discoplea ? (Gallionella .''). Podosphenia Pupula. 



Eunotia gibba. Synedra acuta. 



Fragilaria acuta. constricta ? 



rhabdosoma. Entomon. 



Gloeonema paradoxum ? Sphenosira Catena. 



Gomphonema gracile. Stauroneis linearis. 



Augur. Stauroptera Monogramma. 



Himantidium Arcus. 



Phytolitharia 4. 

 Lithostylidium Clepsammidium. Lithostylidium rude. 



Rajula. Trabecula. 



It is evident from this list that the river water in which the fish 

 was taken contains an admixture of sea animalcules (Coscinodiscus), 

 and consequently is situated either within the tidal reach of the 

 ocean, or, as only fragments of the marine form were noticed, flows 

 over tertiary biolithic deposits. Cocconeis fasciata is likewise a 

 known form from the coast of Peru. 



Synedra Entomon, known hitherto only from Chili, is remarkable 

 from its occurrence in the dust of the trade-winds. Synedra } con- 

 stricta is a smooth form characteristic from its two extremities being 

 drawn out into two long-pointed needles. Stauroneis linearis and 

 Sphenosira Catena are known American forms from Chili and Mexico. 

 Stauroptera Monogramma is a ribbed form resembling the smooth 

 Stauroneis Monogramma from Surinam, which is again similar to but 

 not identical with Achnanthes ventricosa, — Report of the Berlin Aca- 

 demy, Jan. 1848. 



Discovery of the Maxillary Organs of the Iguanodon. 



Dr. Mantell's researches have at length been rewarded by the 

 discovery of portions of both the upper and lower jaw of the Igua- 

 nodon, nearly thirty years after his first announcement of the form 

 and structure of the teeth of that colossal herbivorous reptile. 



The form of the maxillary organs of the Iguanodon is most ex- 

 traordinary, and entirely differs from anything previously known in 

 the class of reptiles. The configuration of the lower jaw approaches 



