24rt ^JI■:^[OIL•S of the QFICEySLAXD MUSEUM. AN ICHTHYOSAURIAN SKULL FROM QUEENSLAND. By Heber a. Longman. F.L.S., Director. Queensland Museum. (Plate.? XV and XVI and Text-figures 1 and 2.") The remains which are the subject of this paper were found at Galah Creek, about twelve miles from Hughenden, in the Rolling Downs formation (Lower Cretaceous) of Western Queensland, and were collected, forwarded, and kindly donated to the Queensland Museum by Mr. S. Dunn and Mr. WilHam Elliott in ilay, 1914. It is my pleasant duty heartily to thank these gentlemen for their enthusiastic work in securing this large and valuable specimen for our collections. Material. — As will be seen from the profile view, illustrated in Plate XV., this large .skull is in six pieces. The extreme end of the rostrum is missing, but, judging from the structure of the anterior part preserved, only a small portion would be needed to complete the skull. Gilmore^ has pointed out how frequently the extreme anterior segment is missing in Ichthyosaurs, and how fractures are caused by the cracking of specimens when enclosed in an elongate concretionarj^ mass. The skull is massive, with a maximum length (mandibular) of 1,026 mm., and a maximum width (articular area of mandible) of 395 mm. It is evident that great changes have taken place since it came to rest. As a result of tremendous vertical pressure, the whole of the teeth, with the exception of broken roots, have l)een forced from the continuous dental grooves, characteristic of Ichthyosaurus, and the premaxillary and mandibular rami are now in juxtapo.sition. Fortunately, many of the teeth have been preserved, mostly as fragments, on the lateral and lower surfaces of the jaw. In the posterior part of the skull there are still greater evidences of changes under intense pressure. On the left-hand side the orbit has been crushed down and its original contours are not distinguishable. As a result of this lateral torsion, the mandible has been somewhat displaced to the right. The supratemporal fossae are preserved in fairly symmetrical condition. Great difficulty has been experienced in studying some of the component parts. The distortion of the skull is accompanied by a very close investiture of the remains by a fine hard lime-stone matrix, which in places is almost indistinguishable from the actual fossil. The matrix involving Cratochelone berneyi,^ described by the author in 1915 from the same district, was very similar in texture. This investing material evidently jienetrated the skull after the decay of cartilage, cementing the disrupted elements together. ^ C. W. Gilmore, Mem. Carnegie Mus., Pitts., II, 1905, p. 80. 2 H. A. Longman, Mem. Qld. Mvis., Ill, 1915, p. 25.
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