352 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Perisomatic Plates of Crinoids.* * * § — Messrs. C. Wacksmutk and F. 
Springer consider that the plates of a Crinoid fall naturally into two 
categories, the primary and secondary or supplementary plates. The 
primary form the fundamental part of a Crinoid, while the supplementary 
pieces serve to fill up spaces. The former may be separated into two 
classes: those developed on the right antimere, which, in one way or 
another, are related to the axial nerve-cords, and those developed on the 
left antimere and connected with the mouth or the annular vessel around 
it. To the first class they refer the stem-joints, basals, underbasals, 
radials, all brachials, whether fixed or free, and the plates of the pinnules ; 
to the second the orals and all plates of the ambulacra to the end of the 
pinnules. The remaining plates are supplementary, and, in the opinion 
of the authors, neither strictly actinal nor abactinal. 
Messrs. Wachsmuth and Springer would apply to all plates interradially 
disposed in the calyx the term interradials, and use interbrachials as a 
general term for all plates between the rays above the radials ; the terms 
“ interdistichals,” “ interpalme[a]rs,” and “ interambulacrals ” explain 
themselves. They conclude with a criticism of some of the recent work 
of Mr. F. A. Bather. 
Ovary of Ophiurids. j — Sig. A. Russo has studied the disruption and 
renewal of the ovarian parenchyma in Ophiothrix fragilis, Ophioderma 
longicauda , and Ophiomixa pentagona. The germinal vesicle and spot 
become hyaline or colloid, or, rarely, undergo fatty degeneration and 
chromatolysis. The vitellus and vitelline membrane also degenerate. 
Meanwhile, however, there is a process of regeneration, in which fresh 
elements are formed from follicular cells. 
Revised List of British Echinoidea.J — Mr. W. E. Hoyle has pre- 
pared a list of British Echinoids, giving some synonymy, brief definitions 
of genera and species, and the distribution in British seas and elsewhere. 
Twenty-nine species are recognized as British ; Forbes, it will be remem- 
bered, enumerated only twelve. The general clarification followed is 
that of Prof. Duncan. 
Anatomy of Synaptidse.§ — Prof. H. Ludwig and Herr P. Bartels 
have investigated the anatomy of these Holothurians. They find that 
adult Synaptids have no radial water-canals. In all cases they found 
the radial nerve accompanied by an epineural space above, and below by 
a pseudhaemal space, but there were no signs of any water-vessel. As 
they are found in the young this reduction helps to support the view 
that the Synaptidae cannot in any way be considered as primitive forms 
of the Holothurioidea. The semilunar valves of the tentacular canals 
were found, under similar conditions, in all the forms examined. Audi- 
tory vesicles were also always present ; a pair is found on each radial 
nerve, at the point where the nerve emerges from the radial piece of the 
calcareous ring ; they are either supplied by a short branch of the radial 
nerve, or they are placed directly on it. The so-called eyes of Synapta 
vittata are undoubtedly sensory organs ; each pigment -spot has an en- 
* Proc. Acad. Nat. Sci. Philadelphia, 1890, pp. 345-92 (2 pis.). 
f Zool. Anzeig., xiv. (1891) pp. 50-9 (15 figs.). 
X Proc. Roy. Phys. Soc. Edinb., 1889-90 (1891) pp. 398-436. 
§ Zool. Anzeig., xiv. (1891; pp. 117-9. 
