354 OLIGOCHAETA 



Our knowledge of this genus is almost entirely due to Vejdovskt; his account 

 has been confirmed and extended in a few directions by Michaelsen (5) and Ude 

 (1). The most salient character of the genus is the absence of setae. These appear 

 to be represented by a series of large clear cells which occupy the precise position 

 that the setae should, were they present; these cells are of large size— according to 

 Vejdovsky's figure of A. bohemica (24, PI- vii. fig. i) one-third of the diameter of the 

 body; they are pear-shaped in form, and have a single nucleus at the base. 

 Michaelsen states that there are more than one nucleus to each of these cells, 

 which, of course, heightens their resemblance to seta-sacs, these structures being 

 usually formed of a group of cells. A. eisenii has two pairs of these bodies, while 

 only one pair, the ventral, is to be found in the other species of the genus. The 

 integument of AvMchaeta is further remarkable for the existence of 'chlorophyll- 

 glands.' There is in A. eisenii one of these to each segment, lying in the mid-dorsal 

 line on a level with the seta-sacs; the chlorophyll-gland consists of a group of 

 gland-cells, which open on to the exterior by a common duct. The chlorophyll in 

 the interior of these cells was proved to be such by Vejdovskt. In A. bohemica 

 there is a row of these glands, surrounding the middle of the segments, and it would 

 appear from Vejdovsky's figure, illustrating these glands, that they are unicellular 

 spherical bodies. Vejdovskt has stated that he never met with similar structures in 

 other Enchytraeidae ; it is possible, however, that Fridericia striata may have similar 

 chlorophyll-glands (see above). 



Michaelsen states that the longitudinal layer of muscles consists of a single layer 

 of hollow fibres, without the additional layer that exists in so many species, such 

 as F. ratzelii. The clitellum (in A. bohemica^aX any rate) occupies only the lateral 

 and ventral regions of the body-wall (cf. Aeolosoma). The dorsal vessel arises from 

 the intestinal sinus in front of the clitellum ; it has three dilated heart-like swellings, the 

 position of which varies according to the species. The salivary gland is unpaired, 

 and opens behind the pharynx ; there is a little confusion about the unpaired character 

 of these glands ; Vejdovskt says in the description of the species A. eisenii (3, p. 6o) : 

 ' Die Speicheldi-iisen stellen kurze,' &c., and again, in the definition of the genus 

 (p. 50) : ' Die Segmentalorgane modificiren sich im ^—^. Segmente zur Speicheldriise.' 

 On a previous page also the same facts are substantially stated. In a later work, 

 however (24, p. 106), Vejdovskt remarks upon the unpaired condition of these glands 

 in the genus Anachaeta (' bei Anachaeta dagegen unpaarig '), though the observations 

 recorded in that work concern, so far as this genus is treated of, the species 

 A. bohemica. Ude (1, p. 98) says that the salivary gland is unpaired in A. eisenii. 



The spermathecae in this genus do not communicate with the lumen of the gut. 



