NOTES ON SOME BRITISH NUDIBRANCHS. 371 



I do not think tliat the inflated shape of tlie cerata and their 

 arrangement on low pedestals are really important characters in Cdlmn, 

 and would define the genus as at present known in the following way. 



Animal llattish, cerata arranged in rows and sometimes rising from 

 a pedestal. No cnidocysts. Ehinophores simple. Corners of anterior 

 margin of foot prolonged into tentacular processes. Penis unarmed. Jaws 

 not denticulate. Eadula a continuous band not divided into separate 

 teeth and merely bearing serrulations on the upper surface. Digestive 

 system much simpler and less ramified than is usual in the ^olididse ; 

 kidney also simple and not ramified. Hermaphrodite gland symmetri- 

 cally arranged on the two sides of the body. 



Though the anatomy of Galma is characterized by a certain simplicity, 

 this simplicity is no doubt not primitive, but secondarily acquired and 

 connected with the unusual diet of the animal, which feeds on the eggs 

 of fish. The nature of the food no doubt explains the degeneration of 

 the radula and perhaps also the absence of cnidocysts (see Grosvenor, 

 " On the Nematocysts of ^Eolids," Proc. Roy. Soc, 1903, vol. Ixxii. No. 486, 

 p. 469). Several of my specimens seemed to be gorged and distended 

 with gelatinous matter, and probably the creatures' habit of thus stuffing 

 themselves accounts for the breadth and simplicity of the alimentary 

 passages. 



CALM A GLAUCOIDES, ALDER & HANCOCK 



Seven specimens received from the Plymouth Laboratory. Two of them 

 resemble Alder and Hancock's figures more than do the others, which 

 are flatter and have swollen, almost ovate cerata. But no differences of 

 structure were found, and as all the specimens were identified at the 

 Laboratory with C. fjlaucoides, it is proljable that tliey were all alike 

 externally when alive. 



The length varies from 10 to 4 and the breadtli from 4 to 2 mm. 

 The general colour is whitish or drab, but varies in detail, because the 

 transparent integuments allow the contents both of the body and of the 

 cerata to be seen. The broad digestive tract with its diverticula is 

 generally coloured a pale dull yellow, but contains here and there blackish 

 masses in the cerata as well as in the main alimentary tract. In two speci- 

 mens these black portions are so large that the general colour appears to 

 be bluish black. At the sides of the body between the cerata the white 

 follicles of the hermaphrodite gland are distinctly visible. The integu- 

 ments are generally brownish at the sides of the liody and at the bases 

 of the cerata. 



The margin of the foot is expanded both in front and at the sides, so 

 as to be considerably wider than the head and body ; anteriorly the foot 

 is rounded, and is produced on each side into a short tentacular process, 



