G26 RECORD OF CURRENT RESEARCHES RELATING TO 



as also in the Hydraclinidae, uncovered by the tubes. These structures 

 are represented in Eijlais by two long rods, which enclose the tracheae 

 for a short distance. Two ridges projecting forwards from the cross- 

 piece enclose the mouth, as in Hydrachna ; behind this the pharynx, 

 which consists of a chitinous groove roofed in above by a lamina of 

 intrinsic and extrinsic muscles, passes backwards within the labium, 

 exactly as in Hydrachna. An oesophagus of the same diameter 

 (O* 25 mm.) traverses the main nervous mass, after rising up ; it enters 

 the lower part of the anterior end of the stomach, thus differing from 

 Pagenstecher's description, but agreeing with Hydrachna again. The 

 stomach's upper surface presents symmetrically arranged lobes, through 

 the spaces between which the vertical body-muscles pass ; the excretory 

 organ, which has been called a fat body, can be just seen in the median 

 line. The cfecal lobes consist of a memhrana propria, lined internally 

 by a thick granular layer containing granular vesicles, but no trace of 

 cell-structure. A similar structure characterizes the stomach-walls, 

 so that Pagenstecher's description of cells here, and his consequent in- 

 terpretation of the organ as a liver, prove erroneous. Probably it has 

 a double function, the biliary secretion being supplied by the brown 

 cells and the granular investing substance, in Hydrachnidae. Possibly 

 the non-cellular mass of Trombidium represents a stage in the break- 

 ing down of these liver cells. There is no direct connection between 

 the stomach and anus. The posterior end of the excretory organ, 

 which has been mistaken for such a connection, is distinguishable by 

 its chalky-white contents ; it has two anterior branches, and contracts 

 posteriorly towards the anus ; no lining ei)ithelium was made out. 

 The buccal glands have a common opening into the mouth, the loop- 

 shaped gland ending in a narrow canal into which the ducts of the 

 rounded glands open. 



Nervous System. — An oval mass represents the brain and ventral 

 ganglia ; the posterior part shows signs of bilateral symmetry. A 

 layer of small cells directly underlies the neurilemma. The twelve 

 pairs of nerves are divided into two divisions, one directed forwards, 

 the other backwards ; but besides these there is an anterior, unpaired 

 nerve, also found in Bhyneolophus, which overlies the oesophagus ; the 

 pair next behind this is the optic pair-, and a pair lying beneath these 

 probably supplies the palps ; the next goes to the maxillee ; two stout 

 pairs following these supply the two front pairs of legs. The two 

 nerves of the fourth pair of legs are but branches of a single nerve. 



Generative Organs. — Treviranus' accoimt of these parts agrees 

 much better than Pagenstecher's with the real state of the case. The 

 ovaries are connected by a short bridge of tissue lying above the 

 generative opening ; the oviducts are directed forwards, and a circular 

 arrangement of the organs round the oi^ening, common in other 

 Arachnida, is thus presented. The number of eggs in the ovary is 

 innumerable, and they range from young elongated forms of • 05 mm. 

 diam,, with distinct germinal vesicle and spot, to mature individuals of 

 •15 mm., clouded by presence of yolk. The long and tortuous ovi- 

 ducts have their basal portions coiled up together; their median 

 segments arc thickened by a special external layer of cells, • 06 mm. 



