396 CETACEA. 



dated horn tliey are arranged more or less in transverse series of oblique folds, an d are 

 much more marked than in the greatly dilated left horn, and it is somewhat remark- 

 able that the spongy texture becomes more pronounced, coarser and thicker as it 

 approaches the right pole of this unfecundated horn, a feature also characteristic of 

 the uterus of I^latanista and to a more limited degree of the Tapir. These are the 

 general facts connected with the appearance of the surface of the gravid uterine 

 mucosa of Orcella. The whole inner surface of the uterus, left and right horns, from 

 the OS uteri internum to both Fallopian orifices was clothed by the chorion as in the 

 case of diffuse placenta generally, but as its intimate relation to the uterine surface 

 had been disturbed before I had an opportunity to remove the foetus, I did not 

 observe the chorionic villi in situ among the cryptose tissue of the uterine mucosa 

 There can be no doubt but that the smooth spots which stud its surface correspond 

 generally and even particularly in a large number of cases, to the bare spots on the 

 uterine mucosa. 



Microscopic structure of the foetal and the gravid uterus. — The recent interest 

 taken in the histology of the unimpregnated and pregnant uterus and of the fcetal 

 membranes generally, but especially in the case of the Cetacean group through 

 the labours of Eschricht,* Meigs,^ EoUeston,^ and more particularly the able 

 memoirs of Prof. Turner,"^ has induced me to record my observations on these 

 structures in such rare forms as Orcella and Platanista. 



Injections of parts were only made in a limited number of instances, but as 

 the specimens had been preserved in alcohol, the injections did not reach the cryptose 

 structure of the uterine mucosa, and only partially so into the chorion ; however, 

 the general characters of the tissues were elucidated. 



In the parietes of the uterus of the almost mature foetus as displayed under a 

 low and a higher magnifying power (Plate XXXVIII, figs. 5 and 6), the free mucous 

 membrane superficially is comparatively smooth, there are few rugae or manifesta- 

 tions of mucous crypts, the membrane is wavy in outline, and any depressions 

 that exist are shallow. The epithelial layer is thin, and the cells are apparently ' 

 cylindrical. The subjacent or true uterine membrane, on the other hand, is rela- 

 tively of considerable thickness, and, as usual, is composed of closely woven delicate 

 connective tissue, everywhere studded with corpuscular bodies, similar to those 

 described by Turner in the gravid uterus of Orca, These corpuscles, together with 

 their nuclei, give it almost a granular appearance. The corpuscles are irregular in 

 shape, subcircular, ovoid or elliptical. The involuntary muscular fibres with much 

 fibro-areolar tissue intermixed, even in this very early condition, form a well 

 marked layer, varying in thickness from a third to a fourth the depth of the pre- 

 ceding. A fibro-serous coat of about equal thickness to the last is in some places 

 partially separated from it by largish blood-vessels which here often run between 



' " Delphini Phocsense gravidi." 



2 journ Acad. Nat. Sc. Philadelphia, 1849, vol. i. p. 267. 



3 Trans. Zool. Soc. vol. v, p. 307. 



4 Trans. Roy. Soc. Edinb. vol. xxvi. and Lectures on the Comp. Anat. of Placenta, etc. 



