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Show 1904.] OF THE roTTO AND SLOW LORI8. 159 to be its typical form. It is quite different in the other, and the difference is not without interest. As will be observed in tlxe accompanying drawing (text-fig. 11,/), the furrow in question is really two fur-rows, one transverse, the other longitudinal, arranged triradiately. I think it not unreasonable to regard the ti-ansverse Text-fig. 11. Dorsal aspect of brain of Nycticebus tardigradus. d., see description in text; /., fissure of Rolando ; s., Sylvian fissure. portion as tlxe fissure of Rolando (Sulcus centralis), and the conditions observable are distinctly more like those of the Potto (see later, p. 160). These new facts account also, it will be observed, fox- the somewhat anomalous bx-acket-like fox-nx of the fissure "/." In both specimens and on both sides there was a small but very clearly marked furrow (d, text-fig. 11) running across the interval between the post-Sylvian and the post-lateral, and as nearly as possible at right angles to both. Its dix-ection is the same in both specimens. Text-fig. 12. Lateral view of brain of Nycticebus tardigradus. Letters as in text-fig. 11. Of Perodicticus potto fewer brains have been examined than of Nycticebus, apparently only four, of which but two have been figured, that described by myself and that described by both Ziehen and Elliot Smith. One matter of intex-est that I a m able to record is the existence of a shallow depression traversed by a blood-vessel, which seems to m e to correspond to the post-lateral sulcus of Nycticebus. Dr. Elliot Smith thinks that the sulcus |
