8d 



pell * observed in the Dugong of the Red Sea (Halicore tabernaculi, 

 R.). This condition of the heart was first noticed by Daubenton in 

 the f oetus of the Manatee ; and is also described by the unfortunate 

 Steller in the genus 'vvorthily consecrated to his name, in which, how- 

 ever, the apical cleft of the heart extended up\vards only one third 

 of the ■vvay to^vards the base. In the Dugong it reaches half-way 

 towards the base. The carnivorous Cetacea do not participate with 

 the herbivorous section in this interesting structure. 



" I fbund in each of the specimens that the foramen ovale was com- 

 pletely closed, and the duetus arteriosus reduced to a thick ligament- 

 ous chord, permeable for a short distsince by an eye-probe from the 

 aorta, \vhere a crescentic sUt still represented the original communi- 

 cation. In the smoothness and evenness of their exterior, and their 

 general form, the auricles of the Dugong resemble those of the Turtle 

 {Chelone) : the appendix can hardly be said to exist in either. The right 

 auricle is larger than the left ; the musculi pectinati are well deve- 

 loped, especially in the left : they are irregularly branched, and vvith 

 many of the small lound f asciculi attached only by their two extre- 

 mities to the auricular parietės. The free wall of the right ventricle 

 scarcely exceeds at any part a line in thickness, and is in many places 

 even less. The tricuspid valve is attached to three fieshy columns 

 by chordce tendinece given off from the sides and not the extremities 

 of the columncB, both of which extremities are implanted in the walls 

 of the ventricles. There are several other columnce carneeB passing 

 freely from one part of the ventricle to another, likę the musculi pec- 

 tinati of the auricles, and which have no connection ■vvith the tricus- 

 pid valve. The mitrai valve is adjusted to its office by attachments 

 to two short and transversely-extended columnce. The thickness of 

 the parietės of the left ventricle varies from half an inch to an inch. 

 The valves at the origins of the great arteries present the usual struc- 

 ture. The primary branches from the arch of the aorta corresponded 

 in each specimen vdth the description and figure by Home. There 

 is one superior cava only, not two as in the elephant. The pulmo- 

 nary veins terminate in the left auricle by a common trunk an inch 

 in length. 



" With respect to the vascular system of the Cetacea, Hunterf, 

 speaking of the true \vhales, observes, " Animals of this tribe have 

 a greater proportion of blood than any other known, and there are 

 many arteries apparently intended as reservoirs for arterial blood ;" 

 and then he proceeds to describe the extraordinary intercostal and 

 intravertebral plexuses in the true Cetacea. As no mention is made 

 in the anatomical descriptions of the herbivorous Cetacea, by Dau- 

 benton, SteUer, Cuvier, Raffles, and Home, respecting the existence 

 or other\vise of similar plexuses in the several specimens examined 

 by them, I pursued \vith much interest this part of the dissection of 

 our Dugongs ; but could detect no trace of this very striking modi- 



* Beschreihung des im RothenMeere vorkommenden Dugong. 4to. Frank- 

 furt, 1833, p. 106. 



t Philos. Trans. 1787, p. 415. 



