126 



DOLPHINS. 



and to intercept all communication between these cavities and the 

 nasal fossae, when pressed in a contrary direction, prevents the 

 water forced into the reservoirs just described, from descending 

 into the nasal fossae ; then the fleshy fibres, which come in the 

 form of rays from all the neighbouring parts of the cranium to be 

 attached to the two bags, by contracting, compress them violently, 

 and expel the water, which escapes externally through the narrow 

 opening of the nares, (called spiracle, vent, or blow-hole,) and 

 forms a jet which sometimes ascends as high as nearly forty feet. 



32, These animals do not chew their food, but swallow it 

 rapidly. Their stomach consists of from five to seven distinct 

 pouches. Many of them have on the back a vertical fin, formed 

 of tendinous matter but which is not sustained by bones. The 

 skin is smooth, and generally without a vestige of hair. 



33. This family is divided into four principal genera, which 

 may be recognised by the following characters : 



(Genera.) 



(Furnished with small ) n 

 conical teeth in both jaws. \ " 

 Without ordinary teeth, ") 

 but armed with a great ^NARWHALS. 

 horizontal tusk. 



CETACEOUS 

 BLOWERS. 



f Teeth in the lower jaw : 

 The head equal j no whalebone, 

 to a third, or one-^ 

 half of the whole | Without teeth : whale- 



length. 



l^bone in the upper jaw. 



~ 

 ^ 



WHALW 



34. Dolphins are divided, according to the form of the head 

 and the presence or absence of a dorsal fin, into Dolphins properly 

 so called, Porpoises, &c. 



35. DOLPHINS PROPERLY so CALLED, Delphinus, are recog- 

 nised by a sort of beak formed by the muzzle, which is more 

 slender than the rest of the head, abruptly separating from the 

 convex forehead: they have a dorsal fin, and a considerable 

 number of conical teeth placed along both jaws ; they count in 

 all from one hundred and sixty eight, to one hundred and ninety, 

 according to the species. 



32. Do these animals chew their food ? What kind of a stomach have 

 they ? Is their skin rough or smooth ? 



33. How is this family divided ? What kind of teeth have Dolphins ? 

 What kind of teeth have Narwhals? Are the heads of these animals ex- 

 ceedingly large ? What kind of teeth have Cachalots ? What kind of teeth 

 have Whales? What is the character of the head of Cachalots and Whales? 



34. How are the Dolphins divided? 



35. How are Dolphins properly so called distinguished ? 



