On the Mechanism of Aquatic Respiration, 131 



145. Tephrodornis apfinis, Blyth. 



. Peculiar to Ceylon, where it affects wooded grass lands ; it is 

 not uncommon about Jaffna, Colombo and Kandy. It is migra- 

 tory, and appears in October. The iris of this species is a 

 greenish yellow. .^ n^iij 



[To be continued.] ^^ ^^.^^ 



!>t)Ol{i lo onn i ikln sk d 



XIV. — On the Mechanism of Aquatic Respiration and on the 



Structure of the Organs of Breathing in Invertebrate Animals. 



By Thomas Williams, M.D. Lond., Licentiate of the Royal 



fy. College of Physicians, formerly Demonstrator on Structural 



^.j^Ji,\\9,iomy at Guy's Hospital, and now of Swansea.. _ . _., ^ _ 



ad jadt r^ „ .. , - ,,,^ -5 maaioaqg giifi 



[Continued from vol. xu. p. 4U8.J r. . l 



Articulata. — The annulose are most naturally succeeded by 

 the articulate classes. The word ' annulose' differs in signifi- 

 cation not more from the word 'articulate,' than in structure 

 the annulose differs from the ai-ticulate animal. In the former 

 a mechanically perfect joint never occurs. An 'articulation,' 

 complete in all its mechanical appliances, is not produced in the 

 animal kingdom below the Myriapod. The feet and tentacles of 

 the Annelid, the spines and hard appendages of the Echinoderra, 

 the soft processes of the Medusan, and the feelers of the Zoophyte 

 are equally remote in construction from the leg of the insect or 

 the claw of the crab. A 'joint' is the symbol of organic supe- 

 riority : it is not an arbitrary symbol ; it is a unit in an assem- 

 blage of signs which proclaim a new and higher combination in 

 the arrangements which constitute 'life.' At this limit in the 

 animal series, the fluids and the solids of the organism undergo 

 a signal exaltation of standard. The system of the chylaqueous 

 fluid exists no longer in the adult organism, — it is present only 

 in the embryonic. It is supplanted by that of the blood-proper. 

 This capital fact supplies the material wherewith the physiologist 

 forges the golden key which is capable of unlocking treasures 

 long hidden from the eye of science. Coincidental ly with the 

 joint y at the frontier of the articulate subkingdom, there occurs 

 a heart to circulate the blood, fibrine, and with it an order of 

 floating corpuscles more highly organized in the fluids; a won- 

 drous development of the muscular apparatus, striae in the muscle- 

 cell, a rapid increase in the dimensions of the cephalic ganglia, 

 and in those of the organs of the special senses. It is here, in 

 the history of the reproductive system, that the dioecious cha- 

 racter is first unquestionably assumed. These are note-worthy 

 events in the ascensive march of organic architecture ! TVhy, at 



9* 



