142 ME. A. H. GAEEOD ON THE MANATEE. 



to the ventral insertion of the limbs there were one or two slight mamilliform 

 thickenings of the integument, which had no deeper-seated glands apparently con- 

 nected with them. 



The vagina is partitioned into two parts by the transverse hymen, in which two small 

 apertures exist, each not more than ^ inch in diameter. The one, the common uroge- 

 nital portion, is 2^ inches long, with the median urethral orifice just in front of the 

 hymenal openings. Between it and the short prepuce-like clitoris is a blind pocket, 

 just large enough to admit the ungual phalanx of the thumb. The true vagina is two 

 inches in length, with slight irregular foldings ; its walls are dense and fibro-cartila- 

 ginous in texture, as is the well-developed os uteri. The uterus closely resembles that 

 of the Dugong, its cornua being 5^ inches long, the body being only 2^ inches. Its 

 lining membrane is longitudinally plicated. 



The rudiment of the urachus is more preserved than usual ; and from the anterior 

 extremity of the bladder a fine tube extends along its axis for a short distance. 



Dr. Murie has described and figured the brain. He, however, mentioned that the 

 specimen he examined was not in the most fit state for investigation. I was able to 

 remove the organ within twenty-four hours of the animal's death, when it was not in 

 the least injured ; my opportunities have therefore been more favourable, and the 

 differences I have detected make me think it better to give fresh illustrations of its 

 conformation. The brain does not present convolutions properly so called. The 

 Sylvian fissure is large and bifurcates high up ; it ceases some way externally to the main 

 longitudinal fissure of the brain ; it also separates sufiiciently at its origin to show the 

 situation of the lohus opertus. A hippocampal sulcus also gives origin to the hippo- 

 campus major. There are distinct indications of a superior frontal sulcus. The cal- 

 loso-marginal sulcus is well marked, continuous, and extends far back, ceasing in front 

 opposite the genu of the corpus callosum. Below this point the frontal lobe extends a 

 great distance, as is cleai'ly shown by Dr. Murie, and it presents slight indications of 

 sulci on its antero-inferior angle {vide PI. XXX.). 



The corpus callosum is short from before backwards, and in a median longitudinal 

 section only covers the anterior and a little of the superior border of the thalamus 

 opticus. Between it and the fornix no septum lucidum is developed, the precom- 

 missural fibres forming a thick median longitudinal plane, extending from the corpus 

 callosum. to the fornix. The anterior white commissure is small, as is the pineal 

 gland. The corpora quadrigemina are not large. 



There is no trace of a posterior horn to the lateral ventricle. The hippocampal sulcus, 

 however, extends so far up above the posterior portion of the thalamus opticus as to 

 develop the basal part of the hippocampus major into a triangular lobule, partly obli- 

 terating the back of the lumen of the cavity of the lateral ventricles, and bounded 

 along its base-line, which runs from behind and externally forwards and inwards, by 

 the ample fringe of the choroid plexus. The anterior horn of each lateral ventricle is 



