156 SUMMARY OF CURRENT RESEARCHES RELATING TO 



burden ; this anus might become more specialised until there appeared 

 a regular " anal segment," the budding zone being always between it 

 and the last-formed bud. If we suppose an increased development of 

 the wall-muscles for locomotion, we can understand how the endoderm 

 and the ectoderm would be gradually divorced from each other by an 

 increasing development of intervening tissue, with spaces for streams 

 of nutritive fluid. Thus mesodermal chambers may be accounted for. 

 *' With the perfection of the powerful neuro-muscular sheath and the 

 necessary mesodermal apparatus for its nutrition and excretion, we have 

 brought our strings of Ccelenterate buds near enough to the typical 

 Annelid to show that, whether this was the true origin of the Annelids 

 or not, it could easily have been so." " The parapodia, whatever 

 specialisation and differentiation they may since have undergone, were 

 originally nothing more than gill-folds, and they arose concomitantly 

 with the rise and concentration of the powerful longitudinal muscles, 

 as these latter required more and more oxygen for their work." 



Ciliated Organs of Hsementeria officinalis. * — Prof. H. Bolsius 

 gives some details as to position and structure of these organs ( = the 

 nephridial funnels of other authors) in this leech. The organs do not 

 occupy the same relative position in the different parts of the body : — 

 {1) in the posterior region of the body they are placed ventrally as in 

 the Glossiphonidae ; (2) on the other hand, those of the anterior region 

 are placed as in the Herpobdellidae, and open into the dorso-lateral 

 lacunae ; (3) between the two sets there are one or two which occupy 

 an intermediate position. In structure the organs on the whole are of 

 the Glossiphonid type, and base (pied), stalk, and lobes can be distin- 

 guished. The base is without a nucleus, and is slender, but of con- 

 siderable lateral extent ; the stalk is short, not very mobile, and has a 

 small nucleus ; the lobes arc freely movable, have each a nucleus, are 

 rounded, and bear a superficial ciliated groove. 



Notes on Clyde Polychsetes. f — Dr. M. I. Newbigin has notes on a 

 variety of Jasminiera elegans St. Jos. (a form of which there seems no 

 previous British record), on the close resemblance between Phyllodoce 

 lamelligera and P. laminosa, on Glycera gigantea, and on Trophonia 

 glauca. 



Fresh-water Polychaete.f — Prof. J. Nusbaum describes a worm found 

 , by Prof. Dybowski (1875) in Lake Baikal — the first instance of a 

 Polychasto in fresh water. He calls it Dyboivscella baicalensis g. et sp. n. 

 In an appendix it is noted that another species, D. godlewski, was found 

 in 1900 in the same lake by Goriajeff, and that Prof. Korotneff reports 

 a similar discovery. 



The worm is 7-8 mm. in length, with twelve segments (two to the 

 head), with thirty to forty gill-like cephalic outgrowths, with a well- 

 developed " collar " on the head-segment in the female, with a pair of 

 short tentacles above the mouth-opening, with somewhat dorsal, rather 

 weakly developed parapodia bearing bristles and hooks, with two coiled 

 kidneys or tubiparous glands in the head, without segmental nephridia 



* La Cellule, xvii. (1900) pp. 267-81 (1 pi.). 



t Communications Millport Station, i. (1900) pp. 1-8. 



I Biol. Centralbl., xxi. (1901) pp. 6-18 (4 tigs.). 



