52 SUMMARY OF CORRENT RESEARCHES RELATING TO 



'Challenger' Nemertea.* — The more interesting general points in 

 the results of Frof. A. A. W. Hubrecht have already been noted in this 

 Journal. | Many of the specimens obtained during the voyage were 

 fragmentary, but they were excellently well preserved for histological 

 purposes ; 19,560 sections were made, all of which were stained with 

 Kanvier's picrocarmine. Garinina is a new genus allied to Carinella ; the 

 name of Eupolia is proposed for the genus of which delle Chiaje's Polia 

 delineata is the type. The anatomy is considered in detail, and the 

 memoir concludes with some general considerations. 



5. Incertse Sedis. 



Parasitic Rotifer — Discopus Synaptae.^: — Tbe Rotifer noticed 

 twenty years since by Prof. E. Ray Lankester as living parasitically 

 in Synaptse at Guernsey has been found on the same Holothurian by 

 Dr. C. Zelinka. The worm is not, however, endoparasitic, but lives as 

 a "free space-parasite" in small pits on the skin. This form, which the 

 author calls Discopus Synaptse g. et sp. n., is one of the Philodinidaa ; 

 it is distinguished from all known genera by the following characters. 

 The foot ends in a sucker with a broad round disc and two short pincers ; 

 there is no contractile vesicle ; the cement-glands are formed of cells 

 attached to the ventral walls in two semicircular rows, and their efferent 

 ducts, after various loopings, divide repeatedly and finally open on the 

 last joint of the foot by means of pores arranged in a circle. The 

 animals exhibit four kinds of movements, they either progress like a 

 leech, or they make tactile movements by extending their bodies, or by 

 moving from right to left, or they swim with the foot retracted and the 

 wheel-organ extended. The skin, which is not at all thick, except in the 

 wheel-organ, proboscis, and foot, consists of a cuticle or syncytial hypo- 

 dermis. The dermo-muscular tube consists of eleven delicate circular 

 muscles, and a dorsal pair of longitudinal muscles, which have the same 

 structure as in Callidina. The muscles of its body-cavity are highly 

 developed, for there are more than twenty pairs with quite definite 

 functions. In the limbs there are two pairs of dorsoventral fibres ; the 

 muscles of the foot are so disposed as to serve for the attachment and 

 fixation of the suctorial apparatus. 



The nervous system consists of a brain lying in front of, and partly 

 on the pharynx, of connected periencephalic ganglia and ganglionic cells, 

 as well as peripheral nerves which are connected with ganglionic cells, 

 muscles, and sensory cells. At the hinder end of the brain is a multi- 

 cellular ganglion, provided with lateral nerve-fibres ; there are ganglia 

 connected with one another, and connecting the brain with a large 

 subcesophageal ganglion. From the two dorsal periencephalic ganglia 

 there arise two dorsal fine nerves which pass to the ganglionic cells on 

 the mid- and hindgut. At the anterior end of the oesophagus there is a 

 unicellular ganglion which sends off fibres anteriorly to the proboscis, 

 laterally to a muscle, and posteriorly to the suboesophageal ganglion. The 

 tactile organ has but one joint, at the end of which are a few stiff setae ; 

 at its base there is a multicellular ganglion, which is connected with the 

 ganglion of the proboscis, and gives off nerves to the cells between the 

 oesophagus and the wheel-organ. The proboscis is also an active organ 



* Keports on the Voyage of H.M.S. ' Challenger,' liv. (1887) 150 pp., 16 pis. 

 t See this Journal, 1887, p. 754. J Zool. Anzeig., x. (1887) pp. 465-8. 



