PLATANISTA. 459 



in front ; the after division of the semilune being narrow and pointed on the left 

 side, and blunt and broad on the right side. The larger posterior lung division is 

 more uniform in contour, its hinder end being unequally emarginate and produced 

 on the right and left sides. 



The entire inner borders of both lungs have irregular crenate edges; in this 

 respect, in their partial segmentation, and in absence of lung bridge and superficial 

 pulmonary glands, differing from what obtains in Orcella (compare PL XXIX, 

 fig. 2). 



Thoracic and Fulmonary Glands. — In mentioning the absence of superficial or 

 sternal pulmonary glands in Flatanista^ it should be pointed out that glandular 

 masses similar in kind are not altogether wanting, but only they are placed deeply 

 at the root of the lungs, and at the base of the heart where they are attached to 

 the pericardium. 



Among these glandular masses may be included what evidently answers to the 

 thyroid bodies. This pair of glands (Pig. 1, th) are of a bilobate figure and He 

 across the trachea at an obtuse angle, where the trachea divides into right and 

 left bronchus. While joined mesially, each thyroid gland is egg-shaped, 1*75 inch 

 long and just under 1 inch in greatest transverse mid-diameter. They are smooth- 

 sm'faced and dense in texture. Their intimate structure is of the usual vescicular 

 and colloid character appertaining to the ordinary constitution of these bodies. 



Less prominent and more deeply situated than the aforesaid is a patch of much 

 smaller and quite irregularly sized and shaped glands {gl. gl. gl.). These dip between 

 the bronchi, extend among the great vessels at the root of the heart, and one long 

 narrow patch crosses the upper pericardial attachment, and sends finger-shaped pro- 

 longations between the vena cava and aorta. Partially covering these, and with the 

 parts in natural position, somewhat overlying the thyroid bodies, there is also on 

 each side a very large superficial gland, between 2 and 3 inches long, and of a 

 kidney shape. Posterior to these and almost touching them is another rounder and 

 flatter, but equally large pair of glands, of a similar appearance to the last. Yet 

 nearer the apex of the heart and likewise attached to the pericardium in continuity 

 with the last — that is, adherent by cellular tissue — is a great broad glandular 

 mass of rounded outline. This dips both behind and in front of the heart almost 

 from root quite to apex. Other scattered nodules of a glandular nature are 

 dispersed promiscuously on the surface of the pulmonary and pericardial serous 

 tissues. 



It seemed to me that all these glands may, more or less, be regarded as coming 

 under the denomination of modified lymphatic glands, whether bronchial or other- 

 wise. In a great measure they agree with the analogous glandular material met 

 with in Orcella (compare fig. 2, gl. gl., PL XXIX), and they also combine in part 

 the nature of the so-called pulmonary glands {p. gl.) of the latter animal. It is 

 quite possible, nay probable, that portions of them may represent either remnants 

 of, or be, permanent Thymus glands ; but on this head I could not satisfy myself of 

 their identity in composition with the well-known foetal Thymus bodies. 



