52 JOURNAL OF MARINE ZOOLOGY AND MICROSCOPY. 



mouth. In both is the same lowly development of sense organs, and 

 want of any defined cephalic or head region. 



The points of divergence are essentially the presence in the 

 Lancelet, of a notochord, of an elongated central nerve-mass, and of 

 a higher type of blood system. 



Finally it is noteworthy that a series of minute tubules, probably 

 excretory, open into the upper portion of the atrial cavity on either 

 side of the pharynx. There can be but little doubt that these 

 represent the paired excretory tubules (nephridia), so characteristic 

 of the worms. Hence, as no kidneys of any vertebrate pattern are 

 present, the Lancelet exhibits in the structure of its renal organs, 

 the most unmistakable of its many plebeian characteristics. 



Explanation of Figs. 13 — 16, Plate IV. 



Ampliioxus lanceolatus (Yarrell). 



Fig. 13. View of a young specimen -iVin. long ; from the left side. 



Fig. 14. Diagram of a transverse section of same through pharyngeal 

 region. 



Fig. 15. Diagram of a transverse section through the anterior end 

 of the body of a typical Ascidian, e.g. A. mentula. 



Fig. 16. Diagrams showing the mode of formation of a double gill 

 slit from a single. 



Lettering the same in all figures, viz. : — ap. atrial pore ; a. anus ; 

 b t. buccal tentacles ; c. cuticle ; df. dorsal fin ; e. eye ; end. endostyle ; 

 ep g. epibranchial groove ; ga. gill arches ; i. intestine ; I. liver ; 

 m. muscles ; n. nerve system ; nt. notochord ; ph. pharynx ; p c. 

 pigment cells ; sp c. spinal cord ; vf. ventral fin. 



A PROGRAMME FOR THE EASTER HOLIDAYS. 



Those who look forward to Easter as a short interval of relaxation from business 

 routine, when perhaps some profitable shore collecting may be accomplished, will 

 note with pleasure that on Good Friday (March 23rd), there occurs one of the highest 

 Spring tides of the year. On the Jersey coast, the vertical rise and fall is 39-ft. 2-in. 

 The Laminarian zone with its varied treasures will be largely uncovered, and any 

 naturalists paying our island a visit will be richly rewarded. On the Friday, we 

 intend to visit by boat the outlying reefs and caverns ; on the Saturday, there will 

 be extensive shore-collecting during the day and at night a moonlight tow-.netting 

 among the islets of the bay in front of the Station. Inclusive charge will be 12/6, 

 with use of laboratory compartment, reagents, utensils, &c. We shall be pleased 

 to answer any enquiries. The Directors, Jersey Biological Station. (See also 

 page 3 of cover). 



TO CORRESPONDENTS 



All communications for the Editor to be addressed to the 

 Biological Station, Jersey. 



Original notes on Marine Life are invited ; while technically 

 correct, they must however be written in an interesting style. 



Advertisements to be sent to the same address. 



