74 SUMMARY OF CURRENT RESEARCHES RELATING TO 



muscles here form a continuous layer, and the longitudinal are arranged 

 in fifteen bundles ; the whole is to be regarded as an appendage of 

 the body. 



The coelom contains a thick whitish fluid containing a considerable 

 number of large spherical cells; nearly all of these have a large 

 vacuole ; they do not, as in Sipunculus, coagulate. 



In the full description of the digestive tract mention is made of the 

 characteristic dental structures which are developed from the lining 

 cuticle ; they are to be regarded as the homologues of the various 

 elevations which are found on the surface of the body ; they are filled 

 internally by a process of the subcuticular layer, the cells of which are 

 considerably elongated. The proctodoeum appears to be very short. 



The nervous system, for a knowledge of the central portion of 

 which we are indebted to Ehlers, is next described ; there is consider- 

 able difficulty in investigating the arrangement of the peripheral 

 nervous system, and specimens preserved in alcohol are of no use ; 

 chromic or picric acids are better. A nerve is given off from the 

 centre of every swelling, and therefore corresponds to the middle of 

 every circular muscular area ; these nerves pass off on either side and 

 extend between the cells of the hypodermis ; in an animal 43 mm. 

 long the peripheral nerves are • 002 mm. vride ; in Priapulus the fibres 

 of the hinder end of the body are a little thicker. The nerves given 

 off from the oesophageal ring pass to the body- wall and to the pharynx ; 

 of the latter there are only four ; they pass between the cells of the 

 subcuticular layer, and extend straight forwards and backwards ; 

 these fibres are connected with one another by circular nerves which 

 are set at right angles to them, and in the same superficial plane ; 

 the circles are so disposed as to correspond with the rows of teeth. 

 Dr. Apel was able to trace the peripheral nerve-fibres between 

 the cells of the hypodermis, to the limiting membrane between the 

 musculature and the subcuticular layer. 



The generative apparatus of the Priapulacees is as yet incompletely 

 known ; the female organs are found to consist of an efferent duct 

 and a ventral lamellar glandular body ; the minute structure of these 

 as of the homologous male organs is described in great detail ; the 

 male organ, like the female, is attached to the body- wall by a mesentery, 

 Ehlers' observations to the contrary being probably due to the poor 

 condition of his specimen. 



Throughout the essay constant reference is made to the work of 

 Ehlers and of Horst, who have both contributed very largely to our 

 knowledge of these worms. 



Pelagic Fauna of the Coast of the Guinea Islands.* — Prof. E. 

 Greef, after a brief general account of the pelagic fauna observed 

 round the Guinea Islands, especially describes the pelagic Annelids. 

 Two new species of Tomopteris were observed— jT. rolasi and T. 

 mariana ; the rosette-shaped organ in the parapodia appears to be 

 glandular and not optic in nature, and the gland is luminous and 

 under the direct influence of the nervous system ; the cephalic seg- 



* Zfitschr. f. Wiss. Zool., xli. (1885) pp. 432-58 (5 pis.). 



