154 Miscellaneous. 



Prof. Owen, and are more intimate than that eminent anatomist 

 seems to think. In fact the nervous chain of these animals is not 

 simply enveloped by the ventral blood-reservoir, and fixed to it in 

 such a way as to be difficult to distinguish from it, but is enclosed 

 in it ; and this reservoir does not consist of a simple interorganic 

 lacuna due to the disappearance of the arterial walls in this por- 

 tion of the animal economy. It is not a case of juxta])osition of 

 the nerves and arteries ; it is a complete ensheathment of the 

 former by the latter. The nerves destined for the integuments 

 alone constitute an exception to this ; they are free, and the vascu- 

 lar walls only accompany them to a small distance from their 

 origin. 



The principal arterial trunks open freely into one another, in 

 such a manner that the blood can traverse a circulatory course 

 without passing through the veins. These ways of communication 

 are wide and easy ; but there are others, formed by the terminal 

 capillaries of the arterial system, which are continuous with 

 the roots of the venous system. The latter is formed in part by 

 interorganic lacunae, in part by tubular vessels with perfectly di- 

 stinct walls and presenting all the characters of true veins. This 

 last mode of organization exists throughout in the substance of the 

 liver. The hepatic veins open into a wide trunk situated on each 

 side at the ventral part of the body, and giving origin to the 

 afferent vessels of the branchiae. The neighbouring muscles are 

 arranged so as to act upon these venous trunks, and can cause alter- 

 nately their contraction or dilatation. The blood which, by means 

 of this mechanism, has traversed the respiratory apparatus, after- 

 wards passes into the pericardiac reservoir. 



The origin of the nerves which go to the different appendages 

 enables us to determine the homologies of these parts, and to esta- 

 blish that in the Limuli there are no antennae, as has been supposed 

 by some anatomists. Lastly, I shall add that the visceral ganglionic 

 system is not composed only of stomato-gastric and augeian ganglia 

 in connexion with the oesophageal collar ; there are also small 

 nervous centres attached to the ganglionic chain, and furnishing 

 branches to the terminal portion of the digestive tube. — Comptes 

 Rendus, Dec. 2, 1872, pp. 1486-1488. 



On the Boomdas (Dendrohyrax arboreus). 

 By Dr. J. E. Gray, F.E.S. &c. 



The British Museum has lately received three skins, with their 

 skulls, of a species of Dendrohyrax from Elands-Post, South-east 

 Africa. 



They appear to be the Boomdas, Dendrohyrax arborem of my 

 monograph. This species was first described by Dr. Andrew Smith 

 as Hyrax arboreus, and is known from the D. dorsalis of the west 

 coast of Africa by the fur being much longer and softer, and the 

 dorsal streak yellowish white ; but the great difference is to be ob- 

 served in the skull. 



