1 882.] Zoology. ion 



The Structure and Development of the Skull in Stur- 

 geons. — Professor W. K. Parker has been working out the devel- 

 opment of the skull in Acipenser ruthenus and A. sturio, the Rus- 

 sian sterlet and the common sturgeon of the shores of Great 

 Britain. The larvae of the sterlet that were dissected varied 

 from one-third to seven-twelfths of an inch in length, yet even in 

 the smallest of these the cartilage was becoming consolidated. In 

 the skull of the sturgeon \\\c syuip/ictir, which supports the mandi- 

 bular and hyoid arches, is a separate cartilage, as in the Selachians, 

 not a mere osseous center as in Lcpidostcus and the Actinopteri ; the 

 peculiar modifications of the primary arches of the face show 

 themselves during chondrification, thus the hyoid arch is from 

 the first, inordinately large, yet in the larva the head of the great 

 subdivided hyoid pier only articulates with the auditory capsule. 



There is no room for doubt that all the branchial arches are 

 developed in the outer walls of the large respiratory pharynx, 

 quite independently of the base of the skull and the fore part of 

 the spinal column. Professor Parker declares that he has come 

 to the conclusion that no true branchial or visceral arches exist in 

 front of the mouth; the first cleft is that between mandible and 

 hyoid, and the first arch, the mandibular. The true axis of the 

 cranial skeleton ends under the fold of the mid-brain, and the 

 " trabecular cranii " are merely fore-growths from the parachor- 

 dals. In the sturgeons the ganoid scutes of the head are so far 

 under the influence of the huge chondrocranium, to which they 

 are applied, that the}- may be called frontal, parietal, etc., yet such 



the Actinopteri. The sturgeons" >n the whole, stand, between the 

 Selachians and the bony ganoids, yet not directly in the line be- 

 tween the Selachians and the bony ganoids, and not directly in the 

 line between any one family of the former and any one family of 

 the latter. Larval sturgeons are miniature sharks in appearance, 

 since for weeks they have a shark-like mouth, true teeth in 

 the throat and on the lips, and very long exposed gills. 



The Amvlolytic and Proteolytic Activity of Pancreatic 

 Extracts. 1 — Dr. W. Roberts gives the result of his researches 

 upon the Amylolytic (sugar-forming), and Proteolytic action of 



tinguish soluble ferments, d, vonfof powers of growth and mul- 

 tiplication, from organized ferments, such as yeast, by giving 



en/ymcs,/ ( ?// ( / ( >'< Uasl,isi\ and J vpsiu, which lattei has the pro- 



by simple boiling. The pancreatic juice of the pig has great 

 diastatic power, since it is capable of transforming four times its 

 weight of dry starch at 40 C, to the point at which it no longer 

 ^roc. Royal Society. May 5th, 1881. 



