494 SUMMARY OF CURRENT RESEARCHES RELATING TO 



type, in which we see an oral and an aboral pole. A free-swimming 

 Entoproctous larva is then formed on the same type as a Kotifer. 

 Granting this, we must suppose that the Bryozoon is the result of a 

 simple change of life ; we know that these larvse often creep about 

 on their oral surface. If this habit were to become permanent we 

 should have in the change of habits a sufficient cause for the meta- 

 morphosis ; the ciliary current carrying food to the mouth would, on 

 passing it, abut against the anal extremity of the vestibule, and would 

 gradually drive this back towards the superior extremity of the larva ; 

 there would thus be produced the rotation, in which the digestive 

 tube would be implicated. We may assume the earlier existence of 

 a group of Probryozoa, free-swimming creatures, of a general Eotifer- 

 form, only represented to-day by the larvae of some of the Entoprocta ; 

 these on taking to creeping would have their form altered by a current 

 of water. 



New Adriatic Bryozoa.* — Dr. Piesser discovered in some material 

 sent him from Eovigno in the Adriatic a Bryozoon, which he found 

 difficult to determine on account of its having some of the characters 

 of Gemellaria and some of Notamia, but he calls it Gemellaria, and 

 considers that the definition of the genus must be widened to receive it. 



It consists of rows of double cells back to back, and the aperture 

 occupies most of the front. A zooecium does not spring immediately 

 from the zooecium below as in Gemellaria loricata, but grows in 

 the manner of Notamia bursaria ; further, at the commencement of 

 each branch instead of a pair of zooecia, there is only one, out of 

 which a pair grow. There are radicle fibres which start from the 

 back of a pair of cells and grow out independently, instead of uniting 

 together and growing in a bundle clown the dorsal surface of the colony. 



The most perplexing point to Dr. Piesser was the occurrence of 

 avicularia at the top of the zocecia, sometimes sessile and very 

 minute, at others they are much larger and pedunculate. He thinks 

 that these characters show that it is a connecting link between 

 Gemellaria and Notamia, and if his interpretation is correct, about 

 which opinions may perhaps vary, we may look upon this as another 

 instance showing that the presence or absence of avicularia cannot 

 often be relied upon for generic division. It may interest Dr. Piesser 

 to know that although this curious species has not previously been 

 described, yet it lives in the Bay of Naples, and has also been found 

 from a locality outside the Mediterranean. 



Arthropoda. 



a. Insecta. 



Sensations of Sight conveyed by the Facet-eye. f— The experi- 

 ments of Grenacher, Dor, and Exner, as to where the rays received 

 by the compound eye of Insects ought to be and are concentrated, led 

 to the most contradictory results, until Grenacher finally established 

 the true view. Several points, however, as to the quality of the 



* Neunter Jahresber. Westfalisch. Provinzial. Vereins fur Wiss. u. Kunst, 



1881 ' 



tAbh. Senckenberg. Naturf. Ges., xii. (1880) pp. 35-123 (3 ph.). 



