REPORT ON THE AMPHTPODA. 



481 



shows a pale, fiue structure, but no opening. They may he seen on the flagellum of tha 

 lower antennse of Gammarus puteanus. 



4. Riechzapfen. These olfactory tubes are on the flagellum of the upper antennse. They have 



a narrower dark-rimmed .stem and a paler, broader body, in which there is a slight indenta- 

 tion at about midway. A cloud of fine granular substance may sometimes be seen issuing 

 from the terminal aperture. 



5. Schuhartige Anhiingsel. Calceoli. These shoe- or slipper-like stalked appendages are supposed 



to belong only to the lower antenna of the male, but it is now known that they occur on 

 both pairs of antennfe and in both sexes. 



In the ordinary bristles, called by de Eougemont tactile bristles, Leydig could not find a nerve, 

 though inclined to regard both the bristle and still more the fine offshoot near the tip as the 

 sheathing of a nerve-end. That Glaus should have seen the nerve in other Crustacea [the 

 Argulidfe] he thinks open to doubt. This doubt Glaus criticizes in " der Org. d. Phron. p. 

 10-11, n. The plumose bristles Leydig had always regarded as tactile bristles, having in 

 other subjects shown how they were placed upon indubitable ganglia. If the view of 

 recent observers, that these are auditory hairs, be justified, the sense of sound, Leydig 

 infers, must be distributed over a considerable portion of the surface of the body, a con- 

 clusion not of necessity to be rejected. 



He defends his attribution of an olfactory function to the " Riechzapfen " against the objections 

 of Grabor in 1877. In the lower animals he considers that the different senses are not 

 necessarily very sharply distinguished, so that one and the same nerve-end-apparatus 

 may serve for the sense of touch, taste and smell, may even not be quite inaccessible to 

 light and sound. He illustrates his meaning by the popular use of the German word 

 " Witteru " (compare English "savour") employed sometimes of taste and sometimes of 

 smell. 



In Gammarug fluviafilis and Gammarus pulex he thinks the eyes are pretty much alike in shape. 

 In both the cornea is smooth and without facets. The crystal cone, he says, consists of 

 four pieces, which can scarcely be correct ; see Note on Grenacher, 1879. In view of the very 

 varying statements of authors on the eye of Gammarus puteanus, he made investigations 

 from which he determines that the optic ganglion is present, but not the eye, though 

 pigment-spots mimicking the eye have led some observers to believe that an eye existed in 

 fact. 



Under the heading, " Ueber die Schalendrlise," Leydig reminds us that in his Naturgesch. d. 

 Daphniden, 1860, pp. 28, 29, he had described his discovery in Gammarus of the 

 homologue of the " green gland " in Astanis, but when he says that O. Sars seven years 

 later only knew of the presence on the lower antennas of " un proems conique dirigc; en has 

 et appelt^ I'epine olfactoire," he is very much in error as to the state of Sars' knowledge. 

 See Note on Sars, 1867. Glaus, in 1879, objects that the name " Schalendruse " has no 

 sense when applied as by Leydig to the gland in the base of the antennae, "sondern passt 

 lediglich fur das in die Schale geruckte Driisenpaar der Phyllopoden, welches der 

 Kieferregion gehort." The pair of glands corresponding to the shell-gland is entirely 

 wanting, he adds, in all developed Malacostraca, and has hitherto been made out only during 

 the larval life in Sergestes and Eup)liausia, while on the other hand in the Phyllupuda and 

 many other Entomostraca the antennary gland corresponding to the green gland of Astacus 

 only exists in the larval stage, but afterwards becomes completely degraded (Der Org. d. 

 Phron., p. 13). 



On the digestive system, Leydig recalls the investigations he had described in 1855 in regard to 

 the stomach, histological structure of the intestine, liver and adipose body. He here 

 remarks that the fat-drops are always colourless, and that in the fatty body of the body 

 cavity, round the intestine, there are besides the fat-drops also layers of those concretions 



(ZOOL. CHALL. EXP. PART Li'VII. — 1887.) Xxx 61 



M>a, 



