New Forms of the Hemichordata. 175 



which are probably applicable to other species of Phoronis, have 

 been made : — 



a. Currents of water with food and other particles pass in between 

 the outer and inner circle of tentacles towards the mouth. They 

 pass out between the expanded tentacles, downwards between those 

 of the outer row, and inwards and upwards between those of the inner. 



b. Another current of water passes in succession over two special 

 patches of nervous epithelium, the nephridial openings and the anal 

 opening, and joins the last-mentioned current. 



c. Most of the particles in the first current come in contact with 

 the tentacles, and are carried on them to the mouth region ; some of 

 these are then carried back on the same tentacles on which they 

 came and dropped off. 



d. The two special patches of nerve tissue on the nerve ring are 

 in a position with regard to currents of water similar to the palleal 

 olfactory organ of Mollusca and probably exercise a similar function. 



e. The nervous tissue at the commencement of the digestive tract 

 appears from the definite rejection of particles after reaching this 

 region to be an organ for the discrimination of food particles, and 

 may be called an organ of taste. 



/. The lophophoral gap between mouth and anus is in the living 

 and expanded animal no wider than the spaces between the tentacles, 

 and plays no special part in the passage of currents of water. 



g. The projecting free part of the lophophoral organ is relatively 

 large and leaf-like in life, and in discharge of ova overlaps the 

 nephridial opening conveying the ovum to the brood cavity in the 

 tentacles. The more glandular part probably supplies the mucus in 

 which ova and embryo are enveloped. The whole organ may be 

 called a glandular oviducal furrow. 



h. The blood (corpuscles and plasma) in the normal condition of 

 the animal passes successively through a median (dorsal?) vessel, 

 two circumcesophageal dilatable vessels, a lateral (ventral ?) vessel, 

 and on again to the median vessel. That is, in these vessels there is 

 a true circulation which, however, becomes oscillatory or partly so 

 under abnormal conditions. 



i. The movement of the blood is oscillatory (to and fro) in the 

 vascular diverticula of the tentacles, the body cavity and the gonads. 

 It is also oscillatory in the small circular vessel at the base of the 

 tentacles. 



j. Eeproduction may take place throughout the year, but is much 

 more marked in the summer months. 



k. This species does not die off annually. 



(4) Ptychodera capensis, a new species of the Enteropneusta. 



