832 MB. r. E. BEDDAEB ON THE [DeC. 3, 



lu 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 apo- 

 neurosis, with which the hyoid cartilage is also in contact. A 

 third muscular slip (fig. 2) from the obliquus also fans out over the 

 diaphragm. 



Kg. 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 Pijya. 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 : — 



" Tunicas nimirum externse [musculus] ab hepate oriundus 

 additur, et musculorum adjacentium fibrae simul accedunt ; sine 

 pulmonis saltem dilaceratione, lacerti musculosi eidem affixi separari 

 nequeimt." ' 



Physiologically, this fan-shaped muscle which spreads out over 

 the back of the lungs in Pij^a seems to be comparable to the muscles 

 which arise from the ribs and spread out over the lungs in birds, 

 and which Huxley regarded ^ as being collectively, and possibly, 

 the homologue of the Mammalian diaphragm. Morphologically, 



^ Mayer gives a different account of the origin of this muscle. "Am merk- 

 wiirdigsten von alien Muskeln ist aber der diesem Thiere eigenthiimliche Lungen- 

 muskel, muse, ptihnonum proprius. Er entepriugt, 14 Linieu breit und J Linie 

 dick, von dem Darmbeiiikamm unterhalb des muse, laiissimus dorsi, geht nach 

 auf- und einwiirts, heftet sich an die hintere Flache des untern Sat-kes der Lunge 

 seiner Seite an, und verbreitet sich niit dicken strahleuforraig 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 ebenfalla von dem Femur, aber an seinem 

 aussern Winkel ist schmal, jedoch dick, tritt unter 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." 



^ " On the Respiratory Organs of Apteryx," P. Z. 8. 1882, p. 560. 



