118 The American Naturalist. (February, 
ing a sort of transitional state. Tiedemann, sixty-eight years 
ago, in a plate which for accuracy puts those of Theodor to the 
blush, represents the hypoglossal nerve taking the origin I have 
ascribed to it, omitting, however, the most cephalic rootlets, 
which are indeed very frail. Since Theodor cites Tiedemann, it 
is remarkable that he could have borne the latter’s excellent 
plates in mind, and in conflict with the real facts designated the 
first cervical as the hypoglossal pair (Plate vin., Fig. 2).° In 
removing the membrane it is very difficult to avoid tearing off 
the hypoglossal nerve roots, and it is doubtless due to this fact, 
and his erroneous naming of the first spinal as the last cranial 
nerve, that Theodor’s non-recognition of the olive is due. 
Although the older writers, particularly Tiedemann, have care- 
fully delineated and described lobules of the cerebellum, and 
especially its vermiform lobe, Theodor in one sentence states 
that the seal has no vermis cerebelli in the sense in which a vermis 
is spoken of in the human cerebellum, and in another proceeds 
to describe it to be an exceedingly complicated body. Much 
dependence cannot be placed on his dissections and figures. I 
have never been able to remove a phocidan cerebellum intact 
without sacrificing the skull; for the lobulus appendicularis, meas- 
uring fully half an inch cephalo-caudal, as much transversely, 
and one-quarter of an inch dorso-ventral, is almost entirely em- 
bedded in bone, and connected with the main cerebellum 
through a small foramen by a pedicle not exceeding a line in 
diameter. Theodor has failed to preserve this morphologically 
important structure, and even to discover his failure to do so, 
although the most superficial acquaintance with the dog’s or cat’s 
brain should have directed his attention to it, particularly in view 
of his sweeping conclusions as to the phylogeny of the marine 
8 Icones cerebri simiarum et quorundum mammalium rariorum, Heidelbergia, 
MDCCCXXI,, Plate 11., Figs. 7 and 8. It is to be remarked that ‘Tiedemann attributes 
olives (o/ive vix conspicuas) to the seal, but locates the figure reference laterad of these 
bodies. The trapeziums he correctly recognizes. 
9 While Tiedemann accurately exhibits the decided caudal direction of the cervical 
nerves from their origin, which is in remarkable contrast with that of the transversely 
running hypoglossal, Theodor tilts = nerve roots in the opposite í airon non. In every 
respect his figures are far behind T to accuracy 

