OCR Text |
Show 1887.] PROF. T. J. PARKER ON CARCHARODON RONDELETII. 35 dorsal lobe, and the spleen (spl.) being an elongated lobulated organ of deep red colour, attached all along the right border of the pyloric division of the stomach and continued on to the dorsal aspect of the cardiac division. 5. The Heart. lhe heart is very large, having the following dimensions in specimen C. centim. Greatest width of ventricle 19 ,, length (antero-posterior) 15 ., „ of conus arteriosus 10-5 ,, width of conus arteriosus 5 ,, ,, of auricle (moderately distended) .... 22 Width of sinu-auricular aperture 9 ,, of auriculo-ventricular aperture 4*5 Thickness of wall of ventricle (about) 3-5 Its general structure is quite normal. The sinu-auricular valves are obliquely right and left; the auriculo-ventricular valves obliquely dorsal and ventral. The coronary veins open apparently by a single very large aperture situated in tbe sinus venosus immediately caudad and dorsad of the left flap of the sinu-auricular valve. The conus arteriosus (Plate VI. fig. 18, con.art.) has three longitudinal rows, each of three valves, one row being dorsal, the others ventro-lateral. The posterior valves (v1) are pocket-like and very thick ; each is connected to the posterior face of the corresponding middle valve (v2) by a strong chorda tendinea, which in the dorsal valve takes the form of a vertical membrane attached to the wall of the conus along its whole length, while in the ventro-lateral valves it is free except at the ends. The middle valves (v2) are very small and thick, forming knobs rather than pouches ; their anterior edges are connected to the walls of the conus by several chorda? tendinea. The anterior valves (v3) are pocket-like and are in close contact with one another at their ed°-es, whereas each of the middle and posterior valves is separated from its fellow by a considerable interval. The edges of each of the anterior valves are produced forwards, forming a firm attachment, but they have no chordce tendinece. There are, as usual, too large coronary arteries placed right and left of the conus. 6. The Urinogenital Organs. The ovary was too much decomposed in specimen C for anything to be made of it; in D it was quite small, so that the specimen must have been immature in spite of its size. The oviducts have the usual character; in D there was a considerable dilatation in the position of the oviducal gland in one oviduct, but only a very slia-ht enlargement in the other. The oviducts open into the external compartment of the cloaca by papilliform terminations (Plate VI. fig. 17, ovd.ap.). |