6 The American Naturalist. [January, 
large funnel cells, which are recognizable before the formation of 
the coelomic cavities. With the formation of the ccelom a row of 
cells buds off from the hinder surface of each dissepiment, just 
behind the funnel cell, to give origin to the tubular portion of the 
nephridium. The anterior myoblasts contribute nothing towards 
the formation of the nephridia, and these organs from the first have 
no structure uniting the successive somites. Bergh thinks that 
Wilson has misinterpreted his sections, and has missed some of 
the stages. The bristle sacs which Wilson thinks are derived from 
the germ-bands are, according to Bergh, formed as ingrowths from 
the ectoderm. With such differences of interpretation it, is diffi- 
cult to say which is right. The work is in each case apparently 
thoroughly done, anda comparison of plates does not serve to 
reconcile the two accounts. 
Benham’s recent paper on the genera and species of earth- 
worms’ will prove of great value to students of the group, and 
an abstract is given here in the hope that it may aid American 
students of the group. The forms occurring in the United States 
are scarcely known. The Oligochztes are divided into: 
NAIDOMORPHA. 
Small worms of relatively few somites; blood uncolored; 
male genital pores in, or in front of, somite vil.; asexual and — 
sexual reproduction; eye spots frequently present; embraces the — 
families Aphanoneura, Naide, Chetogastride, and the genus 
Ctenodrilus, 
LuMBRICOMORPHA. 
Male genital pores behind somite vir.; reproduction only by 
sexual process ; somites behind the peristomium all similar; no 
eye spots. 
The characters separating the two divisions are not constant, | 
except that which refers to the network of blood-vessels on the — 
nephridia. © 
é Benham, W. B. An Attempt to Classify Earthworms. (Quarterly Jour. ete Sois 
XXXI., p. 201, 1890. 
ESETE Sra! Aap Sia OS 5 aa 
SS EE E ee ee ee 
Vee 
= 
