104 Descriptions of Few, 



always marked ; in R. carinata this slit is filled in to form 

 a keel ; in R. formosa it is occupied by a granulated 

 vertical band, dividing below to form a similar band on each 

 side above the aperture ; in the various forms of R. moni- 

 lifera the ovicell is similarly marked, the band in umbonata 

 ending above in a sharp umbo ; in R. tessellata it is not 

 perfectly known, those I have examined, which agree with 

 Hincks' figure, being evidently immature, but it is probably 

 entire, and without special marks. 



In the "Proceedings of the Literary and Philosophical 

 Society of Manchester for 1878," Mr. Waters published a 

 short but very suggestive paper on the use of the opercula 

 in the determination of the Bryozoa. I regret not having 

 been able to procure this paper until quite recently, when the 

 author kindly sent me a copy. Busk, who also had not seen 

 it until long after its publication, has lately figured the 

 opercula and other chitinous organs in a paper on the 

 " Challenger" Celleporse, and shown that they- are of great 

 specific value.* I have examined these parts in all our 

 Reteporas, and find that in many they are very characteristic 

 — in fact, it would be possible to identify most of the species 

 by an examination of the opercula alone. A reference to 

 the figures will show their variations. There can be no 

 doubt that in other genera, especially those in which the 

 real structure of the mouth is so apt to be obscured by the 

 growth of the peristome or the deposition of calcareous 

 matter, the examination of the opercula will give most 

 valuable aid in the discrimination of the species. Whether 

 they will afford characters of higher value must be doubtful 

 until a much larger series has been examined. They have 

 been prepared in the manner adopted by Busk. A fragment 

 is treated with dilute nitric acid for the removal of the 

 calcareous matter, carefully washed in water, soaked in 

 picro-carmine, which stains the chitinous parts yellow, and 

 then teased out with needles in a drop of glycerine. Figures 

 of all the forms are appended. 



I am indebted to Mr. Hincks and Mr. Waters for specimens 

 of the European species for comparison. 



Full details of all our species, for which the drawings are 

 being lithographed, wall shortly be published in Professor 

 M'Coy's" Decades." 



* Journal of Linncsan Society, October, 1881. 



