237 ^* er Schädelbau der Monotremen. 760 



Theil des Hauptes eine dünne Knochenplatte herab, geht senkrecht nach vorn und wird hier cylindrisch, 

 darauf legt sie sich ans Jochbein an, so dass die ganze Schläfengrube durch eine Tafel bedeckt ist, 

 wie dies auch bei den Amphibien vorkommt." 



Owen (1837) wendet sich gegen F. Cuvier und Laurillard zur Bekämpfung ihrer Auffassung des 

 Squamosums als Jugale. Er sagt von Echidna (p. 370, 1. Spalte): „The part described in this Article as 

 a lamelliform portion of the petrous bone, which extends upon the lateral and part of the posterior region 

 of the skull, is regarded by the editors of the Lecons d'anatomie comparee (Ed. 1837), the very able 

 anatomists M. M. Laurillard and Duvernoy, as the squamous portion of the temporal ; and the flat 

 oblong bone, which forms part of the lateral wall of the cranial cavity and the posterior half of the zygo- 

 matic arch, and which supports the articular surface for the lower jaw, is thought to be the malar bone. 

 But when we consider the low development or total disappearance of the malar bone in the skull of the 

 Insectivora generally, as in Eclünops and "üentetes under the Ferae, and as in the Edentate Manis and 

 Myrmecophaga, it is unlikely that the malar bone should attain so superior a size and fulfil such irnportant 

 functions in the Monotrematous Edentata, in which its condition, according to the above views of the 

 editors of the Lecons d'anat. comp., would be unique in the mammiferous class. It appears to 

 me to be more reasonable to regard the malar bone as either altogether absent in the Echidna, as it is in 

 the Manis, and the zygomatic arch as being completed in the Echidna by a greater extension of the 

 zygomatic processes of the temporal and superior maxillary bones; or eise to suppose that they are actually 

 united, at an earlier period, by a separate intervening jugal style, which, however, I have not been more 

 successful in finding than the continuators of Cuvier." 



Vom Om(77iw7!)/nc7M<s-Squamosum giebt Owen eine genaue und deutliche Beschreibung und sagt 

 dann (p. 373, I. Spalte): „I could not find any distinct malar bone in the young Omithorhijnchus. The 

 same arguments against considering the squamous bone to be the malar apply to this Monotreme as have 

 been used in reference to the Echidna. 11 



Später hat Owen angenommen, dass bei Echidna ein Jugale ursprünglich dawar, aber früh mit einem 

 der anliegenden Knochen verwuchs, denn in Anat. of Vert. sagt er (p. 320): „Another mark of ornithic affinity is 

 the confluence of the malar and squamosal, unless the slender process of the maxillary may represent the malar." 



Auf die grosse Merkwürdigkeit des Temporalkanals in vergleichend-anatomischer Hinsicht wurde schon 

 von Meckel (1826) hingewiesen: „Zygoma rem, in nostro animale praecipue attentione dignam, radicem sc. 

 duas posteriores, superiorem et inferiorem offert, quae spatio duarum linearum inter se distant et cum 

 cranio spatium unius lineae latitudinis includunt, forma piscibus, amphibiis, nee non interdum 

 avibus solemnis. 



Echidnarum craniorum inspectio hanc fabricam Monotrematum ordini communem esse doeuit. Differt 

 Echidna ab Ornithorhyncho nonnisi latitudine utriusque radicis longe majore. Foramen canalis hinc nati 

 posterius jam in Echidna indieavi (1808, p. 77 et 82), canalem ipsum ignorans." 



Auch Owen ist derselben Ansicht, dass der Temporalkanal der Monotremen Aehnlichkeit mit der- 

 artigen Bildungen bei Reptilien aufweist (p. 373, 2. Spalte): „The oblique canal, which traverses 

 the squamous suture between the petrous and squamous portions of the temporal in the Echidna is so 

 much shorter and wider in the Omithorhynchus that it appears to detach from the side of the cranium 

 a distinct superior column or root to the posterior commencement of the zygomatic arch. An analogous 

 canal runs between the tympanic" (d. h. Quadratum) „and mastoid bones in the skull of 

 the crocodile 1 ), and is dilated to great width in the Lizards; but the presence of a distinct 



1) Welchen Kanal Owen in dieser Angabe meint, ist mir nicht verständlich. 



