786 MR. A. H. GARROD ON THE [Dec. 2, 



crossed each other like crossed swords, exposing the tail between. 

 In all my specimens the pupil of the eye is circular, and the deep- 

 brown iris complete. These birds were only procurable here for a 

 week. The specimens brought were very thin and much exhausted ; 

 and, curiously, all males. Not a female was to be seen or had ! 

 There can be no doubt that this is a good species, and has nothing to 

 do on the one hand with D. nigripes, Aud., nor on the other with the 

 young of D. brachyura, Temm. Cassin appears to have confounded 

 it with the former, and to have believed it to be the young of the 

 latter. Temminck and Schlegel appear to have figured it in the 

 ' Fauna Japonica ' for the young of I), brachyura ; and I think Gould 

 has made a similar mistake in the 'Birds of Australia.' I do not 

 know the young of D. brachyura ; but these were no young birds, 

 and I would hence crave permission to introduce our bird as a new 

 species under the name Diomedea derogata, sp. nov. 



8. On the Visceral Anatomy of the Ground-Rat (Aulacodus 



swindernianus). By A. H. Garrod, B.A., Prosector to 



the Society. 



[Eeceived December 1, 1873.] 



Our knowledge of the visceral anatomy of the Rodents is still in 

 so incomplete a state, and the prevalent ideas on their classification 

 so correspondingly vague, that until the details of the structure of 

 the most important types have been published, it will be impossible to 

 judge of their mutual affinities. 



I take the present opportunity of noting the most important points 

 in the Ground-Rat {Aulacodus swindernianus) of West and South 

 Africa, a male specimen having very recently died in the Society's 

 Gardens. 



The tongue is elongate and narrow, not divided into an anterior 

 thin, and a posterior deeper portion, but of nearly uniform depth, 

 blunt and rounded at the tip. Among the papillae filiformes of its 

 superior surface, papillae fungiformes are scattered in small numbers. 

 The circumvallate papillae are represented by two long, narrow, elon- 

 gate, circumvallate elevations, one on each side of the median line, 

 where they nearly meet, running forwards as they diverge to form a 

 V. The root of the tongue is covered by large, lax, and scattered 

 conical papillae between those last described and the hyoid bone ; 

 further back it is smooth. 



The salivary glands present no peculiarities ; the submaxillary are 

 the largest. 



The oesophagus, after perforating the diaphragm, runs for half an 

 inch or more in the abdominal cavity before it joins the stomach ; its 

 epithelium, in the inverted stomach, projects beyond the cardiac ori- 

 fice as a stiff puckered tube for about one-eighth of an inch. 



The stomach is simple, proportionally slightly longer than in man, 

 with the pyloric cul-de-sac also a little more developed. Its mucous 

 membrane is smooth, except near the pyloric end, where there are a 



