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Show 1895.] HYDBACHNID POUND IN COBNWALL. 181 widest part, of about "03 mm.; when, however, we come to the construction of the pharynx, and indeed to the question of what really is the pharynx, I do not find that m y species at all agrees with Schaub's description and drawings. Of course, as I have not seen Schaub's species, I cannot in any way deny that he is correct as to that species ; but if he be, then it seems to m e that his species must be quite exceptional, differing entirely not only from what I believe I see in Thyas &c, but also from what Croneberg has described in Eylais, and Henkin in Trombidium. The appearance is so similar in all these cases that the investigator is tempted to doubt whether the difference may not be one of interpretation rather than of actual construction ; it is, however, not merely a difference of small detail but of principle. It we refer to Schaub's Taf. i. fig. 1, we shall find that he draws the pharynx (ph.) as a fusiform sac continuous in a straight line with the oesophagus, and lying above and upon what he calls a chitinous floor (" Chitin Boden ") (his ch. 2), into the top of which floor the long, almost perpendicular, muscles coming from above are inserted; this floor he makes joined at its end to a lower chitinous floor (ch. 1), which forms the true floor of the mouth ; so that the two together form a V with the point directed backward and not allowing any food to pass between the two limbs of the V, or at all events not to pass beyond the point of union of these two limbs. If w e now turn to Schaub's Taf. iii. fig. 6, which is a horizontal section through what he considers to be the pharynx, we find that he considers that organ to be divided into numerous compartments by what he calls disks (" scheibenfor-mige Querflachen " ) , each compartment containing a ring-muscle which constricts an extremely fine tube passing longitudinally up the middle of the pharynx; this tube he says is the true throat (" Schlundrohr " ) , through which the food passes. There is not anything to show how this throat expands again when the ring-muscles are relaxed; it would seem to be probably too delicate to do so from its proper elasticity. If w e now refer to Henkin's figs. 5 and 7, w e shall find that (in Trombidium) he draws most of the similar parts, but puts a totally different interpretation upon them. Schaub's upper chitinous floor (his ch. 2), to which the muscles are attached, is Henkin's "upper wall of the throat"; Schaub's lower chitinousfloor(c/j. 1) is Henkin's "underwall of the throat"; Schaub's disks are represented (in Henkin's fig. 7) by the tendons which attach the long perpendicular muscles (Henkin's " sucking muscles") to the upper wall of the throat; the upper and under walls, when at rest, still form the V shown by Schaub, but they are not joined at the point, and when the sucking-muscles contract the upper wall of the throat is raised, a sucking action is the result, and the food rushes in between the two walls. The fine tube which Schaub calls the throat has not any existence in Henkin's descriptions or figures, nor are any ring-muscles to be found, but the latter are represented by transverse muscles (called by Henkin " swallowing muscles ") in the following manner:-The upper and under walls of the throat are not flat surfaces; they are half-tubes like the rain- |