74 RECOBD OF CURRENT RESEARCHES RELATING TO 



The nervous system of Goplana polonica is described as consist- 

 ing, in young examples, of a cerebroid portion, which, from a lateral 

 view, may be seen to be made up of three succeeding parts, united 

 above to a common stalk ; from this stalk there are given off the 

 nerves for the optic organs and for the oesophageal commissure. 

 Connected with the ganglionic portion there is on either side an 

 irregularly triangular lobe, the tip of which is directed downwards ; 

 the commissures are described as embracing rather the stomach than 

 the oesophagus. There are three abdominal in addition to the seven 

 thoracic ganglia, and the first of the latter group is of a very consider- 

 able size. The auditory hairs were examined in Calliscma BranicJcii ; 

 on the basal joint of the upper antennas we find, in both sexes, very 

 delicate seta3, which are beset at their tip by extremely delicate hairs, 

 and are arranged in two rows ; one row passes to the lower, and the 

 other to the anterior margin of the antennary joint ; of one set of 

 setfB there are fifteen, and of the other thirteen. Each seta is 

 chitinous in structure, and has a tubular basis, which is continued 

 into a goblet-shaped enlargement. The nerves supplying these 

 organs were traced to nearly the extremity, and they, as well as the 

 hairs, showed a very remarkable agreement with the structures of 

 similar function in the Decapodous Crustacea. The author is of 

 opinion that these bodies are undoubtedly auditory in function, but he 

 is careful to point out that all bodies of similar structure may not 

 be the same ; as, for example, the darkly contoured setse on the 

 hiudermost pair of swimming feet found in some amphipods. 



On the fourth and fifth basal joints of the antennte there are to bo 

 observed pale sensory sette, which are more numerous in the male 

 than in the female ; these bodies have a rounded base, and diminish 

 gradually towards their extremity ; they are supplied by the 

 antennary nerve, which forms a ganglionic enlargement in their 

 neighbourhood. The flagellar portion of the lower antennae has its 

 cuticle considerably thickened, and provided with distinct pore-canals ; 

 at the upper margin this thickness suddenly diminishes, and a wide 

 pore-canal is to be observed, in which there is placed a pale seta, to 

 the base of which there is attached a small plate, which is triangular 

 when looked at from the side ; this organ is likewise supplied by 

 the antennary nerve, the branches of which appear to end in the 

 cuticular plate. The writer thinks that these sensory setae very much 

 resemble the tactile flagella described by Hensen as obtaining in tho 

 Decapoda. 



Coming * to the so - called calceoli (slipper-shaped organs of 

 Stebbing), Professor Wrzesniowski states that they are occasionally 

 to be found on the upper, as well as on the lower pair of antennae ; 

 and he confirms the statement of Dybowski as to their not being con- 

 fined to the male sex ; forming a thin-walled, flattened, and stalked 

 vesicle, they have connected with them a large ganglion formed by 

 the antennary nerve. In Gojplana polonica the calceoli appear to be 

 confined to the superior antennae of the male ; there are several 

 present, and each forms a lanceolate plate ; this is, of course, an 



* Loc. cit., p. 487. 



