6o4 



NATURAL SCIENCE. 



abstract of the most important of his observations on the anatomy 

 of Crania tiirbiiiaia, PoH (^^C. rosirata, Hoeninghaus) is appended to 

 Davidson's posthumous Monograph of Recent Brachiopoda (5). 



The study of the circulatory system of the Brachiopoda, Dr. 

 Joubin remarks in the present memoir, is intimately connected with 

 that of the digestive system. It is nothing more than an absorbent 

 lymphatic system with a propellent heart, which directs the nutri- 

 mental fluid derived from the intestine towards the organs of the 

 animal. He passes briefly in review the opinions expressed by 

 Hancock and the older authors who maintained the existence of a 

 regular circulatory system independent of the digestive apparatus, 

 and those of more modern investigators, who absolutely denied the 

 existence of any regular circulatory system. Dr. Joubin held 

 this view so far as Crania ancmala was concerned, and affirmed 

 that he could not discover any structure in that genus comparable 



^3 . 





i-. i^ 



Figure, partly diagrammatic, showing the dorsal surface of the stomach, the base 

 of the arms, a fragment of the dorsal mantle, and the circulatory apparatusof Wald- 

 /!«■>«/« DfHosrt, Sol. (after Joubin). ^.O., aorta; C.C, central heart ; S.ii., brachial sinus; 

 H., cirri ; E., stomach ; /., intestine ; L., lateral hearts ; V.g.s., the superior dilated 

 genital blood vessels; V.g.i., inferior dilated genital bloodvessels; G.g., genital 

 gland ; M., mantle ; Cav. g., general cavity ; T., terminations of the blood vessels; 

 F./., peripheral lacune; C, cilia; C.B., brachial canal at the opening into the 

 general cavity. 



to the circulatory system as described by Hancock. But it is his 

 intention to make further observations in this connection, as his 

 researches on the better developed species Waldhcimia vcnosa have 

 enabled him to recognise the presence of a true vascular system in 

 Waldheimia. He asserts that the heart is in direct relation with the 

 small and numberless lacunes which surround the intestine. These 

 channels are filled with lymph and white globular bodies charged 

 with nutriment. They all terminate at the heart, which is a con- 

 tractile organ, of which he finds Hancock's description to be abso- 

 lutely correct in detail — the disposition of the muscular fibres alone 

 excepted. The " arteries " described by that author differ both in 

 essential structural characters and the nature of their contents frcm 



