Dumeril’s description is of more scientific exactness: ‘Pas de fossettes aux lèvres. On peut aisément reconnaitre les Eunectes seul entre les boa, ils ont les narines percées à la face supérieure du bout du museau et directement tournées vers le ciel.’ These, being extremely small, and with a power to close hermetically, declare its aquatic habits. Its eyes are prominent, and so placed that the reptile can see before it, and also below—that is, down into the waters. On first sight it might be a matter of wonder that so large a serpent should condescend to a meal of rats and mice; but to explain this we must again go back to the early naturalists, when we discover that what Seba called _le rat d’Amerique_ was a rodent quite worth constricting for dinner. Under the order _Muridæ_ were included in those days a number of the larger rodents, such as the Paca, _Mus Braziliensis_; the Coypu, _Mus coypus_; _Myopotamus_, the Capybara; the Murine opossum, and several others, aquatic in their habits, and large enough to attract the ‘Giant of the Waters.’ From the vernacular _Matatoro_, or ‘Bull killer,’ also a whole century of misrepresentations have arisen, the said ‘bull’ being really as small in proportion as the ‘rats’ and ‘mice’ were large. ‘The deer swallower’ is another of its local titles, showing that it is a serpent of varying tastes. Stories are told of this ‘monster’ killing itself in attempting to gorge large animals with enormously extended horns, animals not to be found among the Brazilian fauna; and familiar to most persons are the illustrations of anacondas of untraceable length, the posterior portion coiled round a branch fifty feet high, and the anterior coiled round a bull as big as a prize ox. These illustrations are the offspring of ignorance rather than reality, and though occasionally _Eunectes_ might come to grief by attacking a somewhat unmanageable meal, yet its recognised specific, _murinus_ or _murina_, points more clearly the true nature of its food, viz. rodents of at most some two feet long. No less exaggerated than its appetite is its length. Possibly anacondas may have attained greater size formerly when there were fewer enemies than at present, if it be true, as some have affirmed, that serpents grow all their lives. Thirty feet is the utmost length on record. Wallace affirms that he has never seen one exceeding twenty feet. Those individuals at the Zoological Gardens have rarely exceeded this, and Günther gives twenty-two feet as their average length in the present day.