488 MR. A. D. MICHAEL ON THB 



This organ lias possibly been imperfectly seeu by Karpelles (8) and by Professor 

 Berlese; indeed, it is so conspicuous that no one dealing, even in the roughest manner, 

 with the anatomy of Bdella could help seeing it. In bis great work on tlie Italian 

 Acarina (l), wbich is systematic, not anatomical, Berlese does not say a single word about 

 the internal anatomy of Bdella, but in the introductory portion of liis " Ordo Pro- 

 stigmata " (Trombidiidas) he gives a plate of parts of the striicture of Bdella (chiefly 

 external and the trophi). His fig. 3 is stated to be the rostrum seen from the side, and 

 fig. 4 is stated to be the hypostoma (maxillary lip) seen from below : it is rather a 

 difficult drawing to understand with any certainty, because other organs which 

 lie above the hypostome are shown and there is not anything to indicate that they are seen 

 through the hypostome ; thus the pharynx is drawn, and even the muscles on the dorsal 

 side of the pharynx, although both the hypostome and the pharynx itself must lie 

 between them and the eye of the observer. One of the organs figured, a long way 

 posterior to the hypostome, is a sac, which is, I believe, the sixcking-stomach ; it is 

 lettered "in" and in the explanation of the plate ^' in'" is given as "ingluvies": this 

 is the whole of the information regarding it. Berlese comes tolerably near the function, 

 but he entirely mistakes its anatomy and position in the body ; indeed, his fig. 4 does 

 not agree with his fig. 3 : in the latter the oesophagus only is shown, but in the former 

 the oesophagus, which would lie between the eye of the observer and the sucking- 

 stomach, is not shown at all, and the pharynx is shown as leading straight into the 

 "■ ingluvies," and the hinder portion of the canal as leading directly out of the i^osterior 

 end of the same organ, thus making it a crop forming part of the main line of the canal 

 itself. This is wholly incorrect, unless the species which he has drawn from differs entirely 

 from every Bdella. which I have dissected or sectioned, in all of which the sucking- 

 stomach has been a stalked blind-ended diverticulum of the dorsal side of the oesophagus. 

 Karpelles, if he saw the sucking-stomach at all (8), had previously made practically the 

 same mistake ; indeed he, if I understand his drawng, did a trifle worse, for lie drew tlie 

 sucking-stomach as not only a part of the main tract of the alimentary canal but also 

 as continuous at its i^osterior end with the ventriculus, without any constriction between 

 the two. 



It is, I believe, now generally admitted that the svicking-stomach, although still called 

 by that name, is not really a sticking-organ, biit is a stalked food-reservoir wherein, in 

 the case of Bdella, the juices which have been sucked out of the creature's prey by the 

 action of the pharynx, whicli is the true sucking-apparatus, are stored for a time The 

 sac in Bdella is usually full, or partly full, and the contents are precisely the same as 

 those found in the pharynx, cesophagus, and ventriculus — viz., the blood of the prey tliat 

 the Bdella has been sucking. In two or three specimens of B. Basteri which were 

 picked oft' seaweed, where they had been feasting upon Thysanuridse, and placed 

 immediately in alcohol, a sagittal median section shows this food-mass in the sucking- 

 stomach coagulated and cibsolutely continuous with a thin rod of the same coagukited 

 material in the mouth, pharynx, and oesophagus, and even joined to tlie food-mass in the 

 ventriculus. I have liitherto used the name of " sucking-stomach " for the organ, as it so 

 well known in the Insecta ; but as it gives an erroneous idea of the function, and as the 



