58 SUMMARY OF CUKKENT KESKAKCHES RELATING TO 



Abnormalities in Starfishes. — Giuseppe Zirpolo {Boll. Soc. Nat. 

 Napoli, 1*.>17, 30, 20-29, 4 figs.)- In Echinaster sepositus Gray there is 

 very frequently some abnormality in the arms. Thus there may be six or 

 one may be bifurcated. Figures of these are given. In Asterias 

 ijlacialk 0. F. Miiller variations in the number of arms are much less 

 frequent. Some abnormalities show excess, e.g. six arms, and 'some 

 show defect, e.g. four arms. The abnormality is sometimes due to a re- 

 generative process ; thus the bifurcation of an arm in consequence of 

 some longitudinal lesion may result in six arms. J. A. T. 



Three Madreporic Plates in Astropecten aurantiacus. — Giuseppe 

 Zirpolo {BoU. Soc. Nat. Napoli, 1919, 32, 71-6, 1 fig.) Three quite 

 distinct madreporic plates were found in a specimen of this starfish, a 

 large one and two smaller ones. They communicated independently 

 with the stone canal. J. A. T. 



Partial Regeneration in Astropecten aurantiacus. — Giuseppe 

 Zirpolo {Publ. Stazione Zool. Napoli, 1918, 2, 169-75, 1 pi., 2 figs.). 

 A case in which the loss of two arms has been followed by the growth 

 of a small one at one spot and a mere cicatrix at another. In this way 

 forms with four arms may arise. J. A. T. 



Anomalous Forms of Astropecten aurantiacus. — Giuseppe 



Zirpolo (i)y//. Soc. Nat. Napoli, VM'f^, 31, 100-9, 8 figs.). Instances 

 of three, four, and six arms. The three-armed form is due to the loss 

 of two arms and the absence of regeneration. The four-armed forms 

 are due {a) to the loss of one arm and the absence of regeneration ; 

 {h) to the loss of one arm and the regeneration of one only ; and (c) to 

 the loss of three arms and the regeneration of two only. The six-armed 

 form is probably the outcome of hyper-regeneration. When the lesion 

 does not aifect a large part of the region of the disc, there may be a 

 regeneration of either one arm or of two. J. A. T. 



Regeneration of Arms in Sea-urchin. — Giuseppe Zirpolo {Boll. 

 Soc. Nat. Napoli, 1919. 32, 4.5-50, 1 fig.). A record of a specimen of 

 Sphser echinus granularis in which a deep depression in the test near the 

 al)oral pole shows a distinct zone of regenerated plates. J. A. T. 



Coelentera. 



New Species of Hydra. — Ed. Boecker {Zool. Anzei//., 1920, 51, 

 250-6, 1 fig.). It has been proposed by P. Schulze to divide the genus 

 Hydra into Glorohydra Sch., Hydra L. s. str., and Pelmatohydra Sch. In 

 the genus Hydra s. str. six species have been recognized differing in 

 their cnidoblasts, habit, sex-condition, shape of testes and embryotheca. 

 The author describes a new form, H. ovata sp. n., the term referring to 

 the shape of the larger adhesive cnidoblasts (large glutinants or strepto- 

 lines). It comes nearest to Schulze's H. stellata. J. A. T. 



