ZooL.— Vol. II.] RISEN— OLIGOCHMTA. 145 



cell, but is discontinued in the direction of the diaphragm 

 both upwards and downwards. The lamellae are very dis- 

 tinct and of even thickness throughout until a certain zone 

 is reached, where they spread and thin out, each lamella 

 continuing towards the cell-wall as a thin, wavy, cytoplas- 

 mic thread. In several cells there could be distinctly per- 

 ceived a thinner continuation of the central cell downwards 

 into the muscular layers, probably indicating a connection 

 with nerve-fibers. 



Beddard has given a diagrammatic drawing of a "paci- 

 nian corpuscle" of Hyperiod^'ilus (No. 54, PI. XVI, fig. 4) 

 from which it appears there were a large number of nuclei 

 in the central core. In the sense-corpuscles of Eudrihis 

 EugenicB from Panama there certainly does not exist any 

 structure similar to that just described. On the other hand, 

 I find some resemblance between these cells and the sup- 

 posed auditory cells of Pontoscolex described elsewhere in 

 the paper. In both of these cells the cytoplasm shows a 

 very high degree of differentiation. There is in each cell 

 a central nucleus and a diaphragm, the latter being of 

 different structure in the two cells. In Eudrihis EiigenicB 

 there is no body comparable to the otosome; but still there 

 is enough resemblance to suggest a possible or even prob- 

 able similarity of function. Since the manuscript of the 

 first paper (Eisen 19) on Pontoscolex passed out of my 

 hands. Dr. R. Hesse (2) has described a most interesting 

 type of sense-cells from the epidermis and nerve-ganglia of 

 Lumbricidce. Dr. Hesse recognizes in these cells organs 

 for the perception of light. 



In Pontoscolex and Eudrihis the sense-corpuscles are not 

 found in increased numbers in the anterior and posterior 

 somites, but on the contrary are more numerous in the 

 central parts of the body, or in parts much less exposed to 

 light. If the sense-corpuscles in Eudrihis and Pontoscolex 

 are organs for light, we should expect to find them more 

 numerous in parts of the body most readily exposed to the 

 light, such as the tail arid the prostomium; but in these 



