1 68 NATURAL HISTORY ESSAYS 



comparison with recent forms, one may assume that 

 the stomach of the sea-cow was divided into several 

 chambers, that the lungs were simple, and that the 

 diaphragm, or midriff, was set obliquely in the body 

 to allow them to increase in length.^ Further than 

 this, speculation will hardly take us, and with these 

 words we close our account of the northern sea-cow. 

 The greater includes the less : with the rhytina 

 there perished two species of invertebrate parasitic, 

 one upon it, the other inside. The Cyanmin (or 

 Sirenocvamuvi) rhytinae was a small crustacean 

 which stuck like a whale-louse to its thick skin, 

 swarming in the softer parts of the hide. The 

 cyamum " dimidiam plerumque unciam longa " had 

 a head the size of a millet seed ; it stuck firmly to 

 its host by means of its sharply pointed claws, and 

 obtained nourishment by plunging its beak into the 

 rhytina. Transparent though it was, this parasite 

 did not escape the sharp scrutiny of the seagulls 

 which, perched on the back of the sea-cow, picked 

 up the swarming vermin like rhinoceros birds 

 relieving a buffalo. Then, again, the paunch of 

 the rhytina was infested with white ascarid worms 

 in the single viscus examined by Steller. Unfortu- 

 nately owing to the unwieldly nature of the carcase 



1 Judging from the allied manatee, the hings of the rhytina were like 

 a banana leaf in shape; perhaps Avhen full of air tliey acted in .some 

 degree like a swimming bladder. Certainly the pulmonary organs are 

 well adapted to allow the freest aeration or the blood, as shown in the 

 beautiful arterio-venous tracery exhibited by the injected manatee lungs 

 now in the Royal College of Surgeons' Museum. 



