ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 159 



trochophore furnished with a preoral hood, with a prehuccal vestibule, 

 and with a rudiment of a notochord. It closely recalls the embryo of a 

 Vertebrate at the time when the latter begins to form neural axis and 

 notocbord, but after this point the two embryos diverge rapidly. Whilo 

 the Actinotrocha is a trochophore modified as above, the Vertebrate 

 embryo may be regarded as a reversed trochophore, the anterior region 

 having become the posterior, and vice versa. 



New Enteropneuston.* — W. E. Bitter describes a new Enteropneu- 

 ston from Alaska, Harrimania maculosa g. et sp. n., which he regards 

 as the most primitive of liviug species of that group. It is a littoral 

 non-burrowing form, possessing in the adult, besides a nuchal notochord, 

 an oesophageal one. Tbis consists of a median dorsal ridge and a pair 

 of lateral pockets, and extends along the whole of the collar into the 

 branchial region. Histologically the pockets resemble the nuchal noto- 

 chord, vvhile the ridge has more the character of the general oesophageal 

 wall. The proboscis-pores are persistent ; the gonads are retained in 

 the body-cavity, and are not raised up into genital pleurae. 



Variation in Statoblasts of Pectinatella magnifica.t — Prof. C. B. 

 Davenport has studied the hooks on this Bryozoon from Lake Michigan. 

 The hooks on 827 statoblasts were counted ; the numbers ranged from 

 11 to 21; the mode is 13; average, 13 "782 + *031; index of varia- 

 bility, 1-318 ± -022. The skewness was +0*077; that is, the varia- 

 tion tends in the direction of the larger numbers, and this is corre- 

 lated with the fact that species or races of Pectinatella with much larger 

 numbers of hooks occur. There is a slight hereditary tendency in the 

 statoblasts from one colony, about • 1 when 1 is the maximum inherit- 

 ance. There is an inverse correlation (of — "092 + '006) between the 

 number of hooks and the perimeter, and a larger one between number 

 and size of hooks. The number of hooks is thus not determined by 

 room, nor does it seem to be predetermined from an early stage of 

 development of the statoblast. The hooks show abnormalities, some of 

 which resemble the normal condition of hooks in Cristatella. 



Classification of Cheilostomatous Bryozoa. J — Dr. S. F. Harmer 

 gives reasons for his conviction that a complete rearrangement of the 

 ■Ckeilostomata is required. The division Cellularina in particular is an 

 unnatural one, for it is made up of Cheilostomes which belong to several 

 distinct groups, though agreeing in their dendritic habit. Paying 

 especial attention to the characters of the front-wall (= opercular- wall), 

 the author indicates what the natural grouping may be, but a summary 

 could hardly be shorter than the original, which is a pattern of 

 terseness. 



Rotifera. 



Variation Cycle of Anuraea cochlearis.§ — Dr. Bobert Lauterborn 

 has studied the yearly cycle of variation of this very common rotifer as 

 it occurs in the backwaters of the Bhine by Neuhofen and adjacent 



» Proc. Waskiugtou Acad. Sci., ii. (1900) pp. 111-32 (1 pi.). 



t Ainer. Nat., xxxiv. (1900) pp. 960-8 (6 figs.). 



X Proc. Cambridge Phil. Soc, xi. (1901) pp. 11-17. 



§ Verb.. Naturbiat. Med. Ver. Heidelberg, Bd. vi. 5 (1900) pp. 412-48 (1 pi.). 



