932 RECOBD OF CURRENT RESEARCHES RELATING TO 



upon proved the fact of tlie absorption of the diatoms. The stomachs, 

 intestines, and ffeces were strewed with loric^e of Naviculce. The 

 loricte, being siliceous, are not aifected by the digestive juices, and 

 it would seem extraordinary that with so tenacious a covering their 

 contents should be evolved, were it not for the knowledge of the fact 

 that the covering is not continuous, the line of suture separating the 

 valves composing the frustule being scarcely silicified at all." 



It would therefore appear to be established beyond dispute that 

 the green hue in oysters is due exclusively to their absorption of 

 certain Naviculce contained in the circumambient water. The facts 

 are in perfect keeping with the observations of growers, that heavy 

 rains (which increase the supply of fresh water) cause the disappear- 

 ance of the green from the " clears," while, on the other hand, dry 

 north-east gales, which greatly increase the saturation of the water, 

 bring it, as it is called, " into condition." 



Two points of special interest in connection with the subject 

 remain for future investigation. These are : — 



1. Does the NavicuJa in question remain all the year in the waters 

 where it is found in winter ? 



2. Is the coloration of the beds accidental or temporary ? In 

 other words. Does this alga disappear from the reservoirs when the 

 water changes its colour, or does it become itself discoloured for 

 a time ? 



Neomenia gorgonophilus.* — Dr. A, Kowalevsky has described the 



structure of this new si:)ecies. 



About 2 inches long, it lives parasitically on Gorgonias, creeping 

 about after the manner of a Nemertine. On the lower surface of the 

 body there extends, from the mouth to the anus, an exceedingly delicate 

 ciliated foot. The gelatinous investment of the rest of the body con- 

 sists of (1) a gelatinous substance ; (2) calcareous spicules in a horny 

 basal layer, and (3) epithelial cells of two forms ; in one the cells are 

 short, and in the other elongated. Subjacent to the integument there 

 is a muscular layer, which is especially well developed in the region 

 of the foot, and in this region there are not only longitudinal, but also 

 transversely disposed muscles. The enteric tract is straight, and 

 appears to ojjen posteriorly into a muscular cloaca ; into this there 

 also open the duct of the ovary, and two tubular glands, which are very 

 jjrobably the testicles. There is a supra-oesoiDhageal ganglion, whence 

 arise four longitudinal nerve-trunks, which extend through the whole 

 length of the body ; two are larger and median (pedal) and two smaller 

 and lateral. They are regarded as corresponding to the pedal and 

 branchial trunks of the Chitons. The dorsal vessel, which is best 

 seen in young examples, has a considerable enlargement anteriorly. 

 As to the organs of secretion, the author finds, at the sides of the 

 digestive canal, a large number of cells, which fill up the whole space 

 between it and the walls of the body, and contain rounded concretions, 

 similar to those found in the molluscan organ of Bojanus. Above 

 the dorsal vessel, and on either side of it, there lies the paired ovary. 



* ' Zool. Anzeig.,' ill. (1880) p. 190. 



