325 



NATURE 



[January 31, 1901 



(1) Peripatus jamaicensis, Gr. and Ckll. 



(a) mut. swainsonae, Ckll. 



(b) mut. gossei, Ckll, 



(2) Peripatus jidiformis^ Guild., var. n. gossei, Bouvier. 



Unfortunately, however, the type-specimen of mut. swain- 

 sonae had twenty-nine pa'rs of legs, and was P. julifor mis gossei. 

 This specimen M. Bouvier so identifies, but he overlooks the 

 fact that it is the type of swainsonae, and must therefore bear 

 that name. The dark variety of P. jamaicensis, which M. 

 Bouvier calls mut. swainsonae, may be termed mut. bouvieri, 

 and the proper classification will be as follows : — 



(1) Peripatus jamaicensis, Gr. and Ckll. 



(a) mut. gossei, Ckll. 



{b) mut. bouvieri, Ckll. (swainsonae, Bouv.). 



(2) Peripatus juliformis. Guild., var. swainsonae, Ckll. 

 [gossei, Bouv.) T. D. A. Cockerell. 



East Las Vegas, New Mexico, U.S.A., January 4. 



DASYPELTIS AND THE EGESTED EGG- 

 SHELL. 



A Charming Fact in Natural History. 



A NXIOUS that my pupils should see things about 

 -^~*- which they hear in the course of their class-work, 

 I have recently lodged with the Zoological Society a 

 standing order for an assortment of " quids," which, 

 mostly of the nature of non-assimilable 

 food, with occasionally a gizzard lining, 

 are thrown out at the mouth by certain 

 birds, snakes, and other creatures, in 

 conformance with a habit extending to 

 the anthropoid apes, since even the 

 famous Chimpanzee "Sally" had ac- 

 quired it {P.Z.S., 1885, p. 674) — a habit 

 most marked in certain whales, which 

 will thus egest the whole skin of an 

 animal devoured and flayed before being 

 •digested. 



Among the first set of " castings " 

 which I received were the two pigeons' 

 €gg-shells herein delineated, which were 

 •"thrown" by the egg-eating snake Dasy- 

 peltis scabra during the spring of 1900. 

 This animal, confined to tropical Africa, 

 shares with the Indian Elachistodon the 

 unique feature of possessing vertebral 

 " teeth," recently proved by Kathariner 

 {Zool. Jahrb. Bd. xi. Anat. p. 501) to be, 

 in the African species, true hypapo- 

 physes, toothlike but destitute of enamel, 

 which mostly project towards or into the 

 oesophageal lumen, through its median 

 dorsal wall. The two snakes are mem- 

 bers of distinct sub-families, and, in 

 their isolation and independent occur- 

 rence, they furnish an ideal example of 

 the principle of " convergence," by the process termed 

 by St. Hiliare for Dasypeltis itself the " balancement " 

 and now better known as the "substitution" of organs, 

 as is proved for this snake by Kathariner's assertion 

 that the reduction of its true teeth is effected during 

 ontogeny. Elachistodon is unfortunately known only 

 from two examples, and although it occurs in the Bengal 

 area, it is unrepresented in our national collections. 



Kathariner, in Dasypeltis, describes hypapophyses for 

 each of the first thirty-four vertebrae, and of these the 

 first twenty-six are much swollen basally, their minute 

 pointed extremities lying each within a surrounding 

 oesophageal lip, in such a manner as to suggest that they 

 come into action only under pressure. The remaining 

 eight are elongated, and with the exception of the last 

 are converted into cutting organs, which perforate the 



oesophageal roof when at rest. The feeding habits of this 

 animal have been described by Miss Durham in the 

 P.Z.S., 1896, p. 715, and she states that egestion of 

 the shell occurs on the average one and three-quarter 

 hours after the first seizure of the egg. No observations 

 have hitherto been published on the egg-shell as dis 

 gorged, and unexpected interest attaches to this, from 

 the fact that the two shells herein described differ to a 

 marked extent in the evidence they furnish of the nature 

 of the processes at work. Both agree only in the presence 

 of a deep indentation (Fig. ii. a — a). As examined in the 

 dried shell this gives the impression of a definite rent, 

 through which the egg-contents would appear to have 

 been discharged ; but as its precise nature cannot be 

 decided without maceration, which would lead to a sacri- 

 fice of one of the shells, I leave the settlement of this to 

 the future. Whether it be a cut or a mere depression, it 

 is beyond doubt due to the action of the perforating hypa- 

 pophyses ; for while it is limited to what would appear to 

 be the area of apposition between these and the convex 

 shell surface when in contact, its edges may be inrolled 

 as underpressure from without ; and the main reason I 

 have for doubt is that in the larger egg (Fig. ii.) the shell- 

 membrane {b'), ragged and torn, projects freely from the 

 upper end, as though the discharge of its contents had 

 been there effected. The shell-area surrounding the 

 afore-named indentation (Fig. ii.) is in each case flattened 

 and somewhat irregularly broken up, the whole presenting 



NO. 1 63 I, VOL. 63] 



Rough outline drawings of pigeon's egg-shells orally egested by the egg-eating snake, 

 Dasypeltis scabra, to show fracture lines and limits of the incision for apparent dis:harge 

 of thi contents, a, incision ; b, areas fro n which shell-fragnents have been removed ; 

 b', ruptured shell-membrane ; /, longitudinal fracture lines ; .?, spiral fracture lines ; 

 i, non-flattened surface x ij ; zV, flattened and non-flattened surfaces of a second 

 shell X ij. 



an appearance unquestionably due to pressure, but 

 whether by contact with the anterior or posterior set of 

 hypapophyses, it cannot at present be proved. 



It is concerning the non-flattened shell-area that the 

 conditions are most novel and interesting, for this, though 

 brittle and subjected to a crushing action, is not, as 

 would be imagined, irregularly broken up. The lines of 

 fracture, in places irregular, are for the most part uni- 

 formly recurrent and equidistant. In the shell first 

 examined they were found [s, Fig. i.) to be mostly 

 longitudinally spiral and broken up in the intervening 

 areas by cross-lines either transversely spiral or feebly 

 transverse ; and in consideration of the fact that the 

 pigeon's egg is spirally rotated during its descent of 

 the oviduct and as its shell is superadded, the conclusion 

 suggests itself that the lines of fracture might be those 



