ZOOLOGY A.ND BOTANY. MICROSCOPY. ETC. 239 



the ectodermic tissues surrounding and capping the dorsal-fin spines of 

 primitive Ordovician and Silurian sharks. This ancient tissue shows no 

 evidence of Haversian systems or lamellse. The first appearance of this 

 is in a Devonian lung-fish. The perforating fibres of Sharpey are seen 

 for the first time in the Mosasaurs of the Cretaceous, in a surface lesion 

 of osteoperiostitis. Osteoid tissue is seen in the same lesions, similar in 

 all respects to the osteoid tissue of modern times. Osteosclerosis and 

 osteohypertrophy are sharply marked in the oldest known fractured bone 

 from the Permian of Texas. There has not been much differentiation 

 of bone since the middle of the Palseozoic. J. A. T. 



C, G-eneral. 



Non-exlstencee of Nervous Shell-shock in Fishes and Marine 

 Invertebrates. — Alfred Goldsborough Mayer {Year-hook, Carnegie 

 Institution, Washington, 1917, No. 16, 1S5-6). Experiments at Tortugas 

 show that the nervous systems of fishes and marine invertebrates are ^ 

 remarkably resistant to the inj'urious effects of sudden explosive shocks. 

 Ring-shaped strips of Cassiopea set into pulsation by an induction shock 

 continued the rates of their pulsation waves within three feet of the 

 explosion of a half-stick of dynamite. If the pulsating rings were in 

 glass jars or tin caiis, partly filled with air, the containers were crushed 

 or shattered, but the rings though injured could be restored to normal 

 pulsation by an induction shock if their pulsation had ceased. Bony 

 fishes with no swim-bladder and small sharks were unaffected by an 

 adjacent explosion. Fishes with a swim-bladder were killed, and dissec- 

 tion showed that the swim-bladder had ])urst and that the tissues were 

 crushed in around it, often breaking the vertebral column. Echinoderms 

 and Crustaceans are not affected. Apart from mechanical laceration, and 

 apart from the crushing in of gas-containing cavities, there seems to be 

 little injury to the nervous system. This supports the view that " war- 

 shock " is a psychological rather than a physiological phenomenon. 



J. A. T. 



Functional Correlation of Hypophysis and Thyroid. — John A. 



Larson {Amer. Journ. Physiol., 1919, 49, 55-89). The administration 

 of the anterior lobe of the hypophysis has a very beneficial action on the 

 maintenance and growth of thyroidectomized rat. Apart from the 

 ameliorating effect upon the general condition, the life is definitely 

 prolonged. It may be that there is a direct substitution of pituitary 

 autacoid for the thyroid hormone in a compensatory effect to establish 

 normal metabolism, or the results might be due to a stimulating effect 

 upon the total metabolic process. Further analysis is required. 



J. A. T. 



Corneal Protection in Crawling Animals. — A. Rochon-Davig- 

 NEAUD {Annales cVOculiste, 1916, 18 pp.). In snakes the author finds a 

 transparent shield continuous with the skin, separated from the true 

 cornea by a conjunctival cul-de-sac containing tears. It seems to be a 

 transparent lower eyelid, with a double epithelium, epidermic and con- 

 junctival, as Miiller and Dumeril described. In conger, common eel, 



