. The Cambridge natural history. Zoology. 124 MARSUPIAL " I,ARVAE are the precise equivalents of similar bones in the jMonotreniata. It has been held, but apparently erroneously, that these bones are mere ossifications in the tendons of the external oblique muscle of the abdomen, or of the pyramidalis of the same region; and vestiges have been asserted to exist in the Dog. Such bonelets are undoubtedly present in the Dog ; but it seems clear from their develop- ment in Mai'supials, as structures actual!}- continuous with the median unossified x)or- tion of the symphysis pubis, that the &q
. The Cambridge natural history. Zoology. 124 MARSUPIAL " I,ARVAE are the precise equivalents of similar bones in the jMonotreniata. It has been held, but apparently erroneously, that these bones are mere ossifications in the tendons of the external oblique muscle of the abdomen, or of the pyramidalis of the same region; and vestiges have been asserted to exist in the Dog. Such bonelets are undoubtedly present in the Dog ; but it seems clear from their develop- ment in Mai'supials, as structures actual!}- continuous with the median unossified x)or- tion of the symphysis pubis, that the " marsu]_)ial bones" belong to that part of the skeleton, and that they correspond with the epipubis of certain amphibians and reptiles. The pouch, it may be remarked, exists in a rudimentary form in the males of many Marsupials. The most salient feature in the life- history of the J\Iarsui>ials is the imperfect condition in which the young are The egg is no longer Fig. 60.—Ventral surface of innominate bone of Kan- garoo {Macrojms viajor). X ^. «, Acetabulum ; ab, acetabular border of ilium; is, iliac surface ; ?«., " mar- supial" bone; pb, pubic completely border ; pt, pectineal tu- bercle ; s, symphysis ; si, supra - iliac border ; 55, sacral surface ; tftf, thy- roid foramen ; ti, tuber- osity of ischium. (From Flower's Osti^ology.) laid, as in the Mono- tremes; but curiously enough the ovum, which has the small size of that (if the Eutheria, divides in- at the first division (as Mr. (.'aldwell has shown), and this develop- mental feature may. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harmer, S. F. (Sidney Frederic), Sir, 1862- ed; Shipley, A. E. (Arthur Everett), Sir, 1861-1927. ed. [London, Macmillan and Co. , Limited; New York, The Macmillan Company
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
