76 Miscellaneous. 



case of the latter. At the first glance we scareel}- hesitate, however, 

 to consider this leech as a Glossiphouicl, for the regular repetitiou of 

 the segmentary papillie and of the nephridial pores on every third 

 annulus clearly indicates that the somite is actually composed of 

 three anniili ; moreover the number of the annuli only amounts to 

 sixty-two, and the intestine bears eight pairs of large lateral caeca, 

 of which the last pair is continued for a considerable distance 

 backwards. 



Oq the other hand, our species possesses ten large black eyes, the 

 general appearance of which recalls in a striking manner those of the 

 genus Hcemadipsa., the land-leeches of Malaysia ; the first four pairs 

 of eyes are still contiguous one with another, owing to the reduction 

 of each of the first three somites to a single annulus ; but the fourth 

 and the fifth pairs are separated by one annulus, in consequence of 

 the reduction of somite iv. to two annuli. In other words, the eyes 

 of Hcemadlpsa are borne by the annuli 1, 2,3, 4, and ?, while those 

 of Jlesobdella are found upon the annuli 1, 2, 3, 4, and 6 *. This 

 fact alreadjf indicates a great tendency towards the shortening of 

 the somites. As a matter of fact the somites i.-iii. are each com- 

 posed of a single annulus; somite iv. has two annuli; somites v.- 

 xxii. possess three annuli each ; somite xxiii. has two annuli ; and 

 somite xxiv., which is the last, has a single annulus. A remarkable 

 fact is that the coalescence of the body is accentuated to such a 

 degree that somites sxv. and xxvi., which are functionally less 

 important than those of the anterior extremity, have disappeared 

 without leaving the least trace behind them. 



The apertures of the genital organs occupy their normal situation ; 

 the testis opens upon somite x., between the annuli 21 and 22, the 

 ovary upon somite xi., between the annuli 25 and 2(3. 



The segmentary papillae are disposed precisely as in the Hiru- 

 dinidae ; they form eight longitudinal rows on the dorsal surface, 

 and those of the inner lateral row are in a direct line with the eyes 

 of the last pair. This character forms a further connexion between 

 Mesohdella and the Hirudinidje. Lastly, it may be added that our 

 s])ecle3 has no proboscis, but possesses three little jaws, situated 

 exactly as in the Hirudinidae, and each armed with from fifty-five 

 to sixty teeth. 



To sum up what has been stated : owing to its ambiguous cha- 

 racters Mesohddla brevis connects in a remarkable manner the 

 (irlossiphonidae with the Hirudinidae. Among the latter it is nearest 

 allied to the Haemadipsinae both by its mode of life as well as by 

 the arrangement of its eyes ; but it is clearly distinguished from 

 them, as well as from all the other Hirudinidae, by the high degree 

 of coalescence attained by its somites. The existence of this inter- 

 mediate form shows that the two families which have here been 

 considered are derived from a common stock, from which the Glossi- 

 phonidae have apparently diverged less than the HirudiuidcC. — 

 Comptes Mendus, t. cxvi. no. 9 (I'eb. 27, 1893), pp. 446, 447. 



* The eyes appear to he arranged in the same manner in Ci/clobdeUa 

 (/labra, Weyenbergh, from the Argentine Republic ; but otherwise there 

 is no resemblance between this species and Mesobdella. 



