stomach which precedes it, and from the rectum which follows it; 4th, the rectum, of which the lining membrane is reddish, communicating with the excretory orifice.
The alimentary canal is quite straight. The heart, like the blood-vessels, is filled with red blood, and the annular swelling—in the middle of which the heart is situated—receives a great number of these vessels. This led Dutrochet to regard it as an organ of respiration, akin to lungs. He could discover no trace of those little pouches which, to the number of nine on each side, are found in the Medicinal Leech, Hirudo medicinalis.[1]
With regard to the habits of Trochetia, Dutrochet stales that it does not live in the water, but on moist soil, where it pursues earthworms, on which it preys, and which it swallows piecemeal (par tronçons).[2] When placed in water he found that it died in three or four days—a statement, however, which has received some modification at the hands of later observers. On the whole Dutrochet considered that the annelid in question constitutes a genus intermediate between the Earthworms and the Leeches, but nearer to the latter than to the former.
The few authors who immediately succeeded Dutrochet in noticing this annelid, as Lamarck and De Blainville, apparently added little or nothing from their own observation to what had previously been made known concerning it. Lamarck corrected Dulrochel's generic name from Trocheta to Trochetia,[3] and after pointing out that the genus is distinguished from Hirudo by having the mouth bilabiate, and possessing neither teeth nor eyes, he gives the following salient characters:—"Body long, cylindrical, anteriorly larger, and somewhat flattened posteriorly, and
- ↑ Leeches have no special organ of respiration, the function being performed by the entire skin, and the organ in Hirudo, Aulastoma and Hæmopis, which Lamarck and others thought were two rows of respiratory pouches, and which are absent in Trochetia, are apparently only reservoirs of mucus, perhaps for lubricating the skin.
- ↑ Other observers have remarked that, like Aulastoma, it swallows the worm whole. On examining one of two specimens which Professor Garrod found in the Regent's Park and kindly submitted to me, I drew from its mouth a portion of a small earthworm, which measured fully an inch in length.
- ↑ Agassiz, in his 'Nomenclator Zoologicus,' gives the derivation of this word as τροχος = discus, a plausible but erroneous idea, for it is evident that the genus was intended to be named after its author, but the termination was incorrectly formed by him. Moquin Tandon, however, retains the original spelling, as also does Diessing, in his 'Systema Helminthum,' vol. i., p. 459 (1850), and Johnston, Cat. Brit. Non-parasitical Worms in Brit. Mu>., ]). 45 (1865).
