268 DB. J. MUEIE ON THE OEGANIZATION OF THE CAAING WHALE. 



2. Vascular Channels and Beservoirs. — My notes respecting the great vessels springing 

 from the arch of the aorta were less complete than those of Professor Turner ; I must be 

 content, therefore, to abide by his description — adding that, in his specimen as in mine, 

 three main trunks were given off from the arch (vide fig. 49). 



Of the cranial vascular distribution, circumstances did not permit me to master it in 

 detail. The more notable observations I could make were chiefly regarding a great 

 plexus situated at the inferior base of the skull, and situated with a rete occupying the 

 proximal infundibular cavity of the mandible. I subsequently had an opportunity of 

 investigating the same in Grampus and Lagenorhynchus, where it likewise obtains'. 



The internal maxillary artery having passed deeply behind the lower jaw, and made 

 a bend, sends forwards a long inferior dental artery. As this pursues its course it 

 distributes ramuscles among the fatty matters and plexus presently to be mentioned. 

 The mandibular cavity contains a mass of softish, marrow-like substance, held together 

 by a network of fibrous tissue. Moreover the interstices are occupied with a maze of 

 vascular channels partly composed of arterial and partly of venous capillaries, interwoven 

 irregularly. Next the bone the tissue and vessels are firmly adherent to the periosteum. 

 In some Cetaceans, e. g. the great Balmna mysticetus and Balmnoptera musculus, as I 

 have been myself a witness to, the cavity in question possesses a perfectly enormous 

 amount of oily material. Even in smaller genera the quantity is by no means sparse ; 

 so that the tissues hereabouts as a whole and on section may be compared to blubber 

 surcharged with blood-vessels. Further on, the internal maxillary gives off large mus- 

 cular branches and others forming pterygo-maxillary divisions. These latter were 

 not followed into the cranium. The inferior base of the skull, from the tympanic 

 bone forwards to the maxillary, internally bounded by the levator or sphincter muscle 

 of the postnares, presents one continuous rete mirabile. This spongy network of vessels 

 lies upon a thick layer of fibroid tissue ; and the vessels anastomose with the aforesaid 

 mandibular rete, whilst they likewise appear to intercommunicate with another venous 

 locular network behind and at the root of the Eustachian tube. The venous capillaries 

 collect into a jugular channel, more or less connected with the rete of the neck. 



The facial artery, vein, and nerve emerge from beneath the cephalo-humeral muscle 

 and submaxillary gland below the auditory canal, thence traverse the face. Steno's 

 duct bears them company. There is a vascular plexus behind the ear-tube, and above 

 and overlapping the parotid gland. 



The multitudinous di%isious forming the great rete mirabile of the neck, limb, thorax, 

 and spine bore correspondence to the arrangement of the zoophagous Cete, amply 



' Of original observations on Cetacean cii-culation, after Tyson, Hunter, Meckel, Breschet, and Von Baer, aU 

 well known, those of Stannius commend notice (" Ueber den Verlauf der Arterien bei Delphinus phocce)vx," Miill. 

 Arch. 1841, p. 379) as being simple, explicit, yet fuU of detail. For copious illustration, probably a trifle too 

 diagrammatic, Barkow's plates stand unrivalled, ' Die Blutgefasse vorzuglich die Schlagaderu der Saugethiere,' 

 1864, p. iv. Professor Turner's recent contributions are highly valuable. 



