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Show 832 MR. P. E. BEDDARD ON THE [Dec. 3, In that drawing will be observed another muscle descending, in the position in which the animal is represented, from the ventral body-wall. This muscle is a portion of the sternohyoid, which leaves the anterior larger portion and is inserted just on to the posterior edge of the expanded hyoid cartilage and on to the aponeurosis, with which tbe hyoid cartilage is also in contact. A third muscular slip (fig. 2) from the obliquus also fans out over the diaphragm. Fig. 3. Pipa surinamensis. Dissection to illustrate internal aperture of oviduct (o) borne upon a special membrane shown also in fig. 2. I am not, however, directing attention for the first time to this curious structural peculiarity of Pipa. Breyer, in his memoir upon the anatomy of the frog, figures the lungs and the muscle attached to them, which he describes in the following words :- " Tunicae nimirum externae [musculus] ab hepate oriundus additur, et musculorum adjacentium fibrae simul accedunt; sine pulmonis saltern dilaceratione, lacerti musculosi eidem affixi separari nequeunt." * Physiologically, this fan-shaped muscle which spreads out over the back of the lungs in Pipa seems to be comparable to the muscles which arise from the ribs and spread out over the lungs in birds, and which Huxley regarded 2 as being collectively, and possibly, the homologue of the Mammalian diaphragm. Morphologically, 1 Mayer gives a different account of the origin of this muscle. "Am merk-wiirdigsten von alien Miiskeln ist aber der diesem Thiere eigenthiimlicbe Lungen-muskel, muse, pulmonum proprius. Er entspriugt, 1^ Linien breit und £ Linie dick, von dem Darmbeinkamm unterhalb des muse, latissimus dorsi, geht nach auf- und einwarts, heftet sich an die hintere Flache des untern Sackes der Lunge seiner Seite an, und verbreitet sich mit dicken strahlenformig auseinander-fahrenden Fasern an dieser hinteren Wandung der Lunge." But on a previous page he speaks of a separate muscle running to the pharynx. This musculus abdominis posterior " entspriugt ebenfalls von dem Femur, aber an seinem aussern Winkel ist schmal, jedoch dick, tritt unfcer den latissimus dorsi in die Bauchhohle hinein und erstreckt sich .... nach aufwiirts, indem seine Muskelnfasern an der vordern und hintern Flache des Pharynx sich verbreiten." 2 " O n the Respiratory Organs of Apteryx," P. Z. S. 1882, p. 560. |