376 SUMMARY OF CURRENT RESEARCHES RELATING TO 



byssal attachment reopens the question of the life-history of this im- 

 portant shell-fish ; other forms may also have an unknown byssal stage, 

 and if that be the case the methods hitherto proposed to be adopted in 

 order to secure the young for purposes of transplanting will have to be 

 greatly modified. To obtain the early stages of the young it will be 

 necessary to resort to some forms of "collector," such as is used in 

 oyster-culture, to allow the fry to affix itself. 



Distribution of Unio margaritifer.* — Herr K. Fischer reports the 

 presence of the pearl-bearing Unio in the district of Trier. "Where the 

 water is limy it is not found. 



MoUuscoida. 

 o. Tunicata. 



Tunicata of the Voyage of the ' Challenger.' f — With his third 

 part Prof. W. A. Herdman completes his description of the Tunicates 

 collected by H.M.S. ' Challenger.' He here gives accounts of the 

 Ascidiae salpiformes, the Thaliacea, and the Larvacea, and discusses the 

 affinities and classification of the Tunicata and their probable phylogeny. 

 Altogether twenty-six species of pelagic Tunicata, mostly belonging to 

 the genus Salpa, were collected, and of these nine are new to science. 

 The remarkable deep sea genus Octacnemus of Moseley is made the 

 subject of a new family, the Octacnemidse. Pyrosoma, although now a 

 free-swimming organism, is, in the author's opinion, derived from the 

 fixed compound Ascidians, to the most typical of which it is, through 

 Gcelocormiis huxleyi, directly related. The Synascidise are polyphyletic 

 forms, derived from the simple Ascidiae at three distinct points; they 

 form, therefore, three groups : — (1) the Polystelidae, (2) the Botryllidae, 

 and (3) the remainder, which are more nearly related to particular 

 groups of simple Ascidians than they are to one another. 



Branchial Homologies of Salpa. | — Sig. F. Todaro compares the 

 anatomy and development of Salpa with that of other ^Tunicata, and 

 comes to the general conclusion " that the two large branchial clefts of 

 Saljpse are homologous with the two branchial clefts in Appendicularia, 

 and with the two primary branchial clefts in the Ascidise, while the 

 numerous stigmata or secondary branchial clefts of the Ascidiae are 

 homologous with those of Salpse." 



Relation of Tunicata to Vertebrata. § — M. F. Lahille summarizes 

 his objections to the view that the Tunicata are the ancestors of the 

 Vertebrata. He thinks that the two groups are very distinct from one 

 another, and cites a number of facts to support his contention. 



B. Bryozoa. 



Phoronis Buskii-H — Prof. W. C. M'Intosh reports on a new species 

 of Phoronis dredged by H.M.S. 'Challenger.' He gives a detailed 

 description of its anatomy, but is unable yet to definitely assert the 



* Verh. Nat. Ver. Preuss. Eheinl., xlv. (1888) pp. 292-4. 



X Reports of the Voyage of H.M.S. ' Challenger,' xxvii. part Ixxvi. (1888) 163 pp. 

 (11 pis.). 



I Atti R. Accad. Lincei (Rend.), iv. (1888) pp. 437-44 (2 figs.). 

 § Bull. Soc. d'Hist. Nat. Toulouse, xxii. (1888) pp. xcii.-vi. 



II Reports of the Voyage of H.M.S. ' Challenger,' Zoology, xxvii., part Ixxv., 

 27 pp. (3 pis.). 



