90 Dr. 0. Grimm on some Blind 



of Onesimus are not entirely deprived of the faculty of sight, 

 their eyes do not function in the medium which usually 

 harbours them, i. e. in the submarine mud where they con- 

 stantly dwell. 



But leaving out of consideration the undeveloped eyes, we 

 find in the species of Onesimus no sense-organs on the antennae 

 and other external parts of the body, as in Xiphargus. Nay, 

 the antennae are in them even deprived almost entirely of the 

 usual hairs, which occur only on the lower surface of the 

 upper, and the upper surface of the inferior antennae, and are 

 also very minute and present in small number. On close ex- 

 amination, however, we rind very highly developed, although 

 concealed, sense-organs on the outer lamella? of the maxilli- 

 pedes, which have already been described or figured by dif- 

 ferent authors. These are short thick stumps with rounded 

 ends, which stand in corresponding cylindrical depressions of 

 the lamella, from which they usually have only the rounded 

 portion projecting. Some of them, however, appear much 

 longer, inasmuch as they project more and also have the 

 extremities more acute ; these are the two cylinders standing 

 at the apex of the lamella, which present a transition towards 

 the ordinary seta?, and thus also prove that we have to do 

 with chitinous seta? metamorphosed for a particular purpose*. 

 These taste-cylinders (as 1 will call them) stand in a row 

 along the inner margin of the lamella, their number varying 

 from eight to fourteen in the different species, as also proba- 

 bly according to the age of the individuals. In the interior 

 of the lamella, beneath the oval matrix-cells, there runs a 

 thick nerve-cord which sends off a branch nerve to each taste- 

 cylinder ; these branches are slightly thickened at their 

 entrance into the cylinder, and are afterwards completely lost ; 

 but whether they form a cell in the thickened part, I have 

 been unable to decide f. At any rate the sensitive nature of 



* Similar tactile hairs with more or less developed nerves and nerve- 

 cells occur ordinarily on the parts of the) mouth of the Arthropoda — for 

 example, among the Diptera, as is universally known. But where Prof. 

 Wagner has detected a number of buccal apertures (" Polystomien '') 

 among them is hard to conceive, as is also the case with the "resucking " 

 (Wiedersaugung) of the food (analogous to rumination !!) by flies, also 

 discovered by him. However, as Wagner has found epithelial cells in 

 the saliva of a materialized spirit, and examined the hair of a Chinese 

 lady called up from the spirit-world (with a view to the discovery of 

 the ancestors of the existing Pediculidse ?), we may expect any thing from 

 him (see "Wagner's and Bautleron's spiritualistic writings in the ' Pus- 

 sischer Bothe "). 



t For the investigation of these cylinders Onesimus platyuros and 0. 

 pompoms, as larger species, are more convenient than O. caspius; but, 

 unfortunately, I have only a few specimens of those species. 



