598 SUMMARY OF CURRENT RESEARCHES RELATING TO 



general conclusion of much interest, that there is no strict definition of 

 germinal layers in the development. 



Structure of Carinoma.* — 1). Bergendal has made a study of the 

 structure and affinities of this Nemertine. The head shows the typical 

 body musculature, an external circular layer, and an internal longi- 

 tudinal. The brain lies, as in Heteronemertini, outside the outer 

 circular muscle-layer and inside the outer longitudinal muscle-layer, 

 and not in the middle of a layer, as in Cephalothrix. The histology of 

 the head is discussed at length. 



The cephalic grooves of Carinoma may correspond to the cerebral 

 organs of Carinella ; the mid-gut has deep pouches, as Burger reported. 



It is impossible to regard Carinoma as occupying a position between 

 primitive Nemertines and Hoplonemertini ; it is nearer to Carinella and 

 the Heteronemertini than to Cephalothrix. It probably arose from a 

 form intermediate between Carinellidge and Heteronemertini. The 

 memoir also includes some discussion of Carinella annulata and 

 Hubrechtia. 



Incertee Sedis. 



Ptychodera erythrsea.f — Ch. Gravier describes this species from 

 Djibuti, on the Gulf of Aden. 



Echinoderma. 



Regeneration in Linckia diplax.$ — Vernon L. Kellogg has studied 

 the regeneration of this sky-blue starfish, conspicuous on the surface of 

 the coral reefs guarding the harbour of Apia (Samoa). There seems 

 to be no doubt of the capacity of an arm torn off at some distance from 

 the disc to regenerate a complete new animal from its proximal surface. 

 In a segment of an arm regeneration may proceed at both mutilated 

 ends. Two figures show an arm regenerating a disc with a new mouth 

 and two madreporites (the normal number in this species). 



Merogonic Development of Sea-Urchin Ova. § — M. Krahelska 

 recalls the fact that the first experiments on merogony were made by 

 Rostafinski || in 1877. She has herself worked with the ova of Psam- 

 mechinus microtuberculatus, and finds that normal segmentation occurs 

 only in fragments which have rounded themselves off after separation. 

 Two forms of abnormal development are distinguished, which seem to 

 be due rather to the alteration of the cytoplasmic organisation than to 

 the absence of a female pronucleus. The rounding off, the central 

 localisation of the mitotic figure, and autotomy of much altered portions 

 of the cytoplasm, are all expressions of the self -regulating capacity of 

 the egg-fragment, which seeks to reconstitute normal relations. 



Internal Secretion in Gonads of Phyllophorus urna.l — Ach. 

 Russo and G. Polara have studied the peritoneal investment of the 

 genital casca in this Holothurian. Some of the cells are supporting 



* Lunds Univ. Arsskrift, xxxix. (1903) received 1905, Afd. ii., No. 2, pp. 1-87 

 (2 pis.). t Bull. Mus. Hist. Nat. Paris, 1905, pp. 46-51 (4 figs.). 



\ Journ. Exp. Zool., pp. 353-6 (6 figs.). 



§ Bull. Interuat. Acad. Sci. Cracovie, 1905, pp. 49-65 (3 pis.). 

 || "Dividua ovi natura," Acad. Sci. Cracovie, 1877. 

 i Anat. Anzeig., xxvii. (1905) pp. 13-19 (6 figs.). 



