664 SIR c. ELIOT ON NUDiBRANCHS [June 19, 



alimentary tube in JDoriopsilla miniata and Doridopsis nigra 

 respectively. It should be remembered, however, that these 

 forms may not be typical in all their details, and that other 

 species may show minor variations. 



In Doriopsilla miniata the tube which issues from the proboscis 

 describes a curve below the nerve-collar {cf. Vayssi^re, I. c. 1901 : 

 "II [le tube] decrit un cercle complet en avant du collier nerveux, 

 puis traverse celui-ci), and then passes through the collar and 

 above the buccal 2;an2:lia which touch the collar to the liver. Its 

 diameter is uniform, and its course behind the collar fairly 

 straight. In Doridopsis nigra the nerve-collar lies immediately 

 behind the proboscis. A straight narrow tube runs through it 

 without making any curves until it has passed through the main 

 body of the nervous system. It then makes two conspicuous 

 bends to the right before entering the liver. In the angle between 

 these two bends the tube is constricted, and here are situated two 

 small salivary glands and the buccal ganglia, which latter are 

 united to the nerve-collar by a pair of connectives which run 

 straight and do not follow the bends of the tube. Behind the 

 buccal ganglia the tube dilates and makes another bend to the 

 right before it enters the liver. 



It looks as if the arrangement in Doriopsilla miniata were the 

 more primitive. It is much the same as that found in an ordinary 

 Dorid, except that the radula with its pouch and the whole buccal 

 mass have disappeared, leaving in their place a curved suctorial 

 tube. But in Doridopsis nigra this curved tube has been pulled 

 backwards through the nerve-collar, and the buccal ganglia have 

 moved with it, and if, as it is reasonable to suppose, the buccal 

 ganglia mark the commencement of the oesophagus, that organ 

 has very different dimensions in the two genera. Though nothing 

 is known about the food of the Doridopsidae, it is clear that their 

 alimentary organs form an exsertile proboscis and a powerful 

 suctorial apparatus ; and perhaps the arrangement found in 

 Doridopsis nigra (which seems to be by far the most usual in 

 the family) allows this apparatus, which probably expands and 

 contracts when taking nutrition, to move more freely. 



Doridopsis nigra (PI. XLVII. figs. 5 & 7) has not only the two 

 small salivary glands already mentioned, but also a large bilobed 

 gland (PI. XLYII. figs. 5 d & 7 d) discharging by a single duct, 

 which enters the wall of the proboscis rather far back, runs 

 forward as a thin tube (PI. XLVII. fig. 5 e) in the lower wall 

 of the proboscis, and opens close to the mouth. It is generally 

 known as the ptyaline gland, but, as Hancock suggests, it may 

 supply a secretion which can pierce or benumb the animal's prey. 

 Neither salivary nor ptyaline glands could be found in my spe- 

 cimens of Doriopsilla oniniata, and if present at all they must be 

 small. Bergh reports their presence in Doriopsilla areolata and 

 D. pallida, but could not find them in D. Icevis (Siboga, p. 179), 

 which offers many analogies to D. miniata. The large develop- 

 ment of the ptyaline gland in Doridopsis would doubtless be 



