662 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Eyes of Selachians.* — V. Franz gives an account of the physiology 

 of the lens and iris musculature, the structure of the tapeturn lucidum, 

 of the cornea, as well as other points. The eye appears to be less essen- 

 tial in Selachii than in Teleosts ; the well developed smelling organ and 

 pressure system (jelly tubes) acting as compensatory. The iris muscu- 

 lature is not sensitive to electric stimuli ; the conjunctiva functions as a 

 membrane impervious to water, and the cornea is without an endothelium. 

 It would appear that the ancestors of the Selachii possessed a processus 

 falciformis which concealed the nerves and vessels of the still function- 

 ing, but now rudimentary, lens muscle. 



Peculiar Group of Rays.f — V. Gratzianow describes Brachioptsra 

 rhinoceros g. et sp. n. from Singapore, and Phanerocephalus ellioti g. et sp. n. 

 from the Indian Ocean — two peculiar forms, requiring a special group, 

 or perhaps family (Branchiopteridre). In the first, the foremost parts 

 of the pectoral fins extend beyond the upturned rostrum, are hook- 

 shaped, and turned outwards and forwards. Both surfaces of the body 

 are quite smooth. In the second, the head is quite separate from the 

 pectorals, which are much broader than those of BranchiopUra. The 

 anterior ends of the pectorals are directed forwards and somewhat 

 inwards, and there are two large incisions between the fins and the head. 

 There are no spines on the back or tail. 



New Abyssal Fish.| — L. Dollo describes Neobythites brucei sp. n., 

 a single specimen of which was captured by the Scottish Antarctic 

 Expedition conducted by W. S. Bruce. He distinguishes it from the 

 only other species, N. digittatus Garman, and discusses the systematic 

 position of the family Brotulidae to which it belongs. The characters 

 adaptive to " benthic " life are the macruriform body, the gephyrocercal 

 tail, the lanceolate rays of the ventrals and pectorals, and the nature of 

 the branchial spines. This new form is an interesting companion to 

 Bathydraco scotice obtained on the same expedition. 



Vascular System of Young Ammoccete.§— C. I. Cori gives a detailed 

 account of the vascular system of the larva of Petromyzon fluviatilis, 

 which, more than any other Vertebrate, displays what may be regarded 

 as primitive and simple conditions. From what is present in the Animo- 

 ccete all the vascular arrangements in higher Vertebrates may be derived. 

 The study of the vascular system in this type lends no support to Dohrn's 

 view that the Cyclostomes are derivable from Selachians. 



Cranial and Spinal Ganglia in Amphioxus.|| — J. B. Johnston 

 finds that the nervous system of Amphioxus agrees with that of lower 

 fishes in the following respects : — (1) It is dorsal, hollow, with separate 

 dorsal and ventral roots, and with a brain ventricle. (2) The dorsal 

 roots consist of general cutaneous, visceral sensory, and visceral motor 

 components. They contain also in the head region fibres of special 



* Jena Zeitschr. f. Naturwiss., n.f. xxxiv. (1906) pp. 429-69 (10 figs.). 



t Zool. Anzeig., xxx. (1906) pp. 399-406 (2 figs.). 



% Proc. R, Soc. Edinburgh, xxvi. (1906) pp. 172-81. 



§ Arbeit. Zool. Inst. Univ. Wien, xvi. (1906) pp. 217-312 (3 pis. and 2 figs.). 



|| Biol. Bulletin, ix. (1905) pp. 112-27 (7 figs.). 



