INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 579 



tion, tlie mouth or tlie end corresponding to the mouth is peculiar 

 to each separate animal, and does not form part of the common 

 colony. 



Genital Organs of Asterina gibbosa.* — Dr. Hubert Ludwig, who 

 has devoted considerable time to the study of the Echinoderms, now 

 reports that, in the examination of the generative organs of the 

 Asteroida, he has come across a very remarkable and quite unexpected 

 arrangement. In all cases which have as yet been observed, the 

 genital organs of the Asteroida have been found to open on the dorsal 

 surface of the disk, and zoologists wei'e coming to believe that this 

 arrangement was an important aid in distinguishing between the Sea- 

 stars (Starfishes proper) and the OpMurida (Brittle-stars) ; it was 

 therefore a matter of some astonishment to find in Asterina gibhosa 

 Forbes ( = Asterisciis verruculatus M. Tr.) the genital orifices on the 

 ventral side, and that the more since in Asterina pentagona E. v. 

 Martens they are on the dorsal side. The first supposition that the 

 arrangement was " pathological " was corrected by the examination of 

 twelve specimens ; in all of these it was observed that in every inter- 

 radial region there were two slit-like pores, set symmetrically to the 

 median plane of the interradius, and parallel to the adjacent ambula- 

 cral groove. Counting from the corner of the mouth, we find the slits 

 between the fifth and sixth interambulacral plates ; each opening leads 

 into a canal, the inner siirface of whose walls is thrown into longitu- 

 dinal folds ; this canal passes in a curved direction to the dorsal wall 

 of the body, where it enters the basal portion of the genital tubes ; 

 these latter, it should be observed, have just the same position as in 

 A. pentagona. 



It is somewhat difficult to imagine what has caused the difference 

 in the position of the pores, but Dr. Ludwig imagines that they have 

 merely changed their position in A. gibbosa, and that it is not a newly 

 developed arrangement. The allied species, A. cephcea Edm. Perrier, 

 has been examined, and has been found to have the genital pores 

 dorsal in position, while the species of F. Gasco, A. panceri, is shown 

 to be merely a variety of A. gibbosa. Pahnipes memhranaceus is reported 

 to have been examined by Gasco, who did not find the genital orifices 

 on the ventral surface ; but as this author does not seem to have been 

 struck by the peculiarity exhibited by A. gibbosa as compared with the 

 rest of the Asteroida, it is only possible to say of it that its genital 

 orifices have not yet been observed. 



Anatomy of Brisinga.j — Dr. Ludwig also contributes a paper on 

 this most interesting form, which is regarded by Sars, its discoverer, 

 as forming the type of a special family of the Asterida, and by 

 Professor Gegenbaur as the representative of a group distinct both 

 from the Asterida and Ophiurida. 



Dealing first with the blood-vascular system, as to the existence 

 of which Sars was not able to convince himself, the author com- 

 mences by recapitulating the results of his investigations on the 



* ' Zeitsch. wiss. Zool.,' xxxi. (1878) p. 395. t ll:>i<'l., p. 216. 



