NOTES OF A COLLECTION OF CALIFORNIAN NUDIBRANCHS. 45 



The buccal mass contains a circular armature of rather thick rods of various 

 shapes, some bent. In the roof of the mouth is a single mandible, t)right 

 yellow and roughly square in shape with a lilunt triangular point on the cut- 

 ting edge. The hinder part of it is membranous. The radula is colourless, 

 and consists of 17 rows containing 18 hamate teeth on each side. Near the 

 rhachis they are smaller and crowded, the hook is low and the base long. 

 They increase in size outwards up to the last but one The outermost of all 

 is rather smaller. They have a wing-like process on the inner margin. 



As Ap(iirp>i alhihjjunrtatu)i is recorded from the Californian coast, the pre- 

 sent animal should probably be referred to it, though points of difference are 

 not wanting. The loss of the white dots in a preserved specimen is not sur- 

 prising, but there are also differences in the shape of the oral veil and bran- 

 chial valves. liut in nudibranchs which bear tubercles and processes these 

 organs exhibit great variation, and it would be unsafe to assume that the 

 arrangement found in a single specimen is specifically characteristic. It is 

 assumed that in saying the pleural teeth of Ae. albo-punctafus are similar in 

 form, Mac Farland does not mean to say that the inner ones are not smaller 

 than the rest, as is usual in the genus. 



The various species of Aer/ires are not sharply distinguished, and neither 

 this specimen nor the typical Ae. albo-puiidatux differ materially from Ae. 

 puncfilucerift, except in colour. 



The forms hitherto described are : — 



1 . Ae punrJilurerts, d' Orbigny. 



2. Ae. hispidus, Hesse. 



3. Ae. leiickarUi, Verany. 



4. Ae. alho-p>un('tatutt, Mac Farland. 



5. Ae. mllosuf, Farran. 



Dirona, Mac Farland, MS., nov. gen. 



Though the following will probably be the first printed account of this 

 remarkable genus, I learn from Prof. Mac Farland, who has most courteously 

 supplied me with much valual)le information, that he has been at )Ie to pre- 

 pare a much fuller description based on the examination of many living 

 animals and preserved specimens. It would appear that some time may 

 elapse lefore his paper is issued, and I, therefore, publish the following notes, 

 which are necessarily imperfect on account of the scantiness of the material 

 at my disposal, but at the same time I preserve his generic and specific names. 



The generic characters are as foUowes : — The animal is aeolidiform in 

 appearance and bears papillae of various sizes, sometimes studded with knobs 

 and ridges, but nut containing cnidocysts or hepatic diverticula. It has no 

 oral tentacles, liut perfoliate rhinophores without sheaths, and an oral veil 

 without projections. The anus lies on the right side very far back The 

 jaws are large and smooth. Tiie radula consists of several rows of five teeth 

 each • the central tooth is small ; the first lateral di-nticulate, the secon(l 



