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Show 1 9 0 6 .] RESPIRATORY SYSTEMS IN THE OPBIDIA. 5 2 3 Coluber calenifer agrees in most respects with Coluber melano-leucus, and these species, together with two or three others, have been placed in a genus apart, viz. *Pityophis. The trachea in the same way extends a long way down the lung, further, indeed, than in Coluber melanoleucus. I traced the tracheal gutter some way behind the liver, in fact to a point about two inches behind that organ and close to the gall-bladder. In this region of the body the lung has ceased to be vascular. As in the last species, the lung-tissue is sharply marked off anteriorly and there is an anterior diverticulum of the lung. Nor could I find the orifice of a second lung. Transverse sections of the lung in the vascular part of that organ showed precisely the same features as have been indicated in describing Coluber melanoleucus. The structure of the trachea and lung, in fact, of the present species shows a slightly exaggerated replica of the structure of the same parts in Coluber melanoleucus. Coluber catenifer var. sayi.-I have examined a snake which is thus labelled, but I am not aware by whom it was identified. It forms part of a small collection of Snakes in spirit belonging to the Society. In Boulenger's ‘ Catalogue of Snakes in the British Museum,' " Coluber catenifer var. sayi " is placed under Coluber melanoleucus, which is distinguished from C. catenifer. In the example referred to here, I find absolutely no difference from the lungs of Coluber catenifer as described above. So alike are they that I find no occasion for a description f. * Of the 45 species of Coluber described by Boulenger (Catalogue of Snakes in the British Museum, vol. ii. 1894, pp. 29 et seq.) the two above mentioned are the only species in which only one labial scale forms a part of the margin of the eye and there are two suboculars. In four other species which have been assigned to the genus Pityophis both of these characters do not occur. The presence of a subocular segmented off from the preocular is common and occurs, I may take this opportunity of remarking, in an example of Coluber longissimus which I have examined, on one side of the head with indications of approaching separation on the other. This point is not mentioned by Boulenger in his definition of the species and is therefore, I presume, not usual. I am able therefore here to correlate a peculiarity of internal structure with an external modification, viz. in the scaling of the head. But without a more exhaustive survey of the structure of the species of Coluber, it would be unwise to attempt generic rearrangements. f It is clear therefore that the question of the species requires some consideration. I extract from Boulenger's description in the Catalogue (p. 68j the following features as distinctive of the two, viz.:- C. catenifer. Rostral as broad as deep or slightly deeper. Anterior chin-shields longer than the posterior. Subcaudal scales more than 65. C. melanoleucus. Rostral much deeper than broad. Parietals usually broken up behind. Anterior chin-shields much longer than the posterior. Subcaudals less than 65. Some or all of labials with black sutures. The other characters used either overlap or are not diagnostic so far as these two species are concerned. In one specimen of C. catenifer and two of C. melanoleucus belonging to the Society I distinguish the above-mentioned characters with the exception of the black ed^es of the labial, which occur in both species. In the latter the subcaudal scales were 48 and 57 pairs respectively; in the single specimen of C. catenifer 71 pairs. In this specimen, the prefrontals were not broken up, as is the case, according to Cope (P. U. S. Nat. Mus. 1892), with C. wilkesii; there was a subocular below the preocular and one subocular below the two postoculars. In the two specimens of C. melanoleucus there was no subocular in front and one below the two postoculars. In all other respects, save colour, these several individuals agreed with Boulenger's description. Yet Baird & Girard (Cat. N. Amer. Reptiles in Mus. Smiths. Inst. |