22 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Pelagic Animals.* — E. Schmidtlein gives a tabular list of 

 pelagic animals, with the numbers of each seen near Naples during 

 the twelve months of 1879 respectively. As to time of appearance, 

 the pelagic fauna of Naples includes animals found — 



(A.) From October to May. By far the most extensive category. 

 Accordingly, a division of the year into two seasons, term and vaca- 

 tion, seems easy and natural. Here belong most pelagic Mollusca, 

 Ctenophora, and Hydrozoa, excepting the higher Medusae. 



(B.) From June to October. This period is characterized by the 

 predominance of Medusae Phanerocarpi. Siphonophora and Hydro- 

 medusae are rare. Swarms of Salpce and of Eucharis, with other 

 animals belonging to the next category, also appear. 



(C.) All the year round. 



(D.) After prevailing storms. Velella especially may be ex- 

 pected with certainty after severe south-east and south-west gales. 

 Porpita is rarer, seldom occurring in fleets. The very much scarcer 

 Physalia suddenly became numerous during the spring. With the 

 fleets of Velella, such visitors as lanfhina, Lepas fascicularis, and 

 pelagic cephalopods likewise showed themselves. 



(E.) At unforeseen epochs. Pyrosoma, rare in 1875 and 1879, 

 was frequent in June 1877. PterotracJiea, common during the spring 

 of 1879, scarcely presented itself the following year. Charyhdea, 

 of which previously but isolated individuals had been seen, became 

 more abundant in November 1879. Next month, for the first time, 

 swarmed Oceania pileata. A beautiful ^quorea likewise abounded 

 in July and August of the same year. 



Mollusca. 



Mutual Affinities of the Cuttle-fishes.j — The most useful 

 summary of our knowledge of the Cephalopoda, with due reference 

 both to systematic and zootomical details, is still that of Keferstein 

 in Bronn's ' Thier-reich,' 1865. A modification of Keferstein's 

 arrangement has lately been proposed by Dr. Brock.J The same 

 observer identified with Troschel's Thysanoteuthis rliomhus a female 

 cuttle-fish caught in the Gulf of Naples during the winter of 1879-80. 

 This specimen, nearly half a metre in length, has been dissected by 

 Dr. W. J. Vigelius, whose views as to its affinities agree in the main 

 with those of Keferstein. 



Thysanoteuthis is plainly an annectant form, related both to 

 Oigopsidae and Myopsidfe. It is most like Ommastrephes in the former 

 group. But it resembles the Myopsidee, and particularly Loligo, in 

 such characters as the shape and structure of the arterial heart, the 

 habitus and mode of branching of the abdominal aorta, and the forma- 

 tion of the ovarium. Its ganglia stellata have no transverse com- 

 missure. Moreover, the conspicuously developed papillae of its 

 urinary sac are without known representatives in the other Oigop- 

 sidae. 



* See reference under " Marine Organisms in Captivity." 

 t MT. Zool. Stat. Neapel. ii. (1880) pp. 150-61 (3 figs.). 

 X See this Journal, iii. (1880) p. 601. 



