PROCHORDATA. 



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Tabulation of structures concerned in the formation of the anterior trematic complex of the 

 Prochordata, consisting of organs which are probably homogenetic and of their connections which are 

 presumably related through metaleptic succession or substitution. 



I. Enteropneosta. 



II. TONICATA. 



III. Cephalochorda. 



Proboscis 



with a head-cavity or proboscis 

 coelom communicating by a coe- 

 lomic orifice with the proboscis 

 pore-canal (or end-vesicle) which 

 opens externally by the proboscis- 

 pore in the vicinity of the anterior 

 neuropore. 



Organ of fixation 



with a cavity in which mesen- 

 chyme-cells circulate ; probably a 

 degenerate coelomic cavity but 

 neither blastocoel nor haemocoel ; 

 it is a deuterocoel sui generis. 



Rostrum 



with a head-cavity which becomes 

 divided in the embryo into right 

 and left portions, the former con- 

 stituting the rostral cavity and the 

 latter the praeoral pit of the larva 

 and the ciliary cotnplex at the roof 

 and sides of the oral hood in the 

 adult. The praeoral pit repre- 

 sents, inter alia, the coelomic 

 orifice of I., being removed from 

 dorsal surface by intervention of 

 notochord ; physiologically it is 

 comparable with the dorsal tubercle 

 of II. 



Proboscis pore-canal 



which, as indicated above, opens 

 externally near to or in common 

 with the anterior neuropore. 



Neuro-hypophysial canal 



or duct of the subneural gland. 

 It arises in primary continuity 

 with the wall of the cerebral vesicle 

 with which it remains in com- 

 munication in the larva by an 

 intracerebral orifice ; at the other 

 (oral) end it opens into the vesti- 

 bule of the branchial sac by an 

 intrabuccal orifice which gives rise 

 to the dorsal tubercle of the adult. 



Olfactory pit 



into which the anterior neuropore 

 opens in the larva. 



Ventral mouth 



of larva and adult. 



Dorsal mouth 



of larva (with which the neuro- 

 hypophysial canal communicates) 

 becoming the buccal siphon of 

 adult. 



Sinistral mouth 



of larva (separated together with 

 the praeoral pit from association 

 with the neuropore by intervention 

 of notochord) becoming the median 

 ventral velum in the adult, the 

 innervation of which, according to 

 the discovery of Professor Van 

 Wijhe, remains sinistral. 



Having obtained the necessary permission from the authorities of the French 

 administration I left Noumea on July 18 on board a local steamer for the Isle of Pines, 

 accomplishing the journey of 65 miles in nine hours. The southern coast of New 

 Caledonia is studded locally with forests of Araucaria, and the Isle of Pines is a hilly 

 satellite of the larger island, and likewise affords some exquisite coast scenery. It is used 

 as a penitentiary establishment, the native population being confined to a reservation on 

 one side of the island, the most picturesque side, where it is controlled by the Mission 

 authorities under the direction of Pere Lambert, who is a renowned conchologist. I paid 



