644 MR J. T. CUNNINGHAM AND MR G. A. RAMAGE ON THE 



on the 3rd segment. We have come to the conclusion that there is nothing 

 in front of the anterior transverse filaments except buccal somite and proeoral 

 lobe, the latter bearing the eyes. The buccal somite is longer than in most 

 cases, equal in length to three of the succeeding somites. Longitudinal sections 

 show that there are no mesenteries corresponding to the superficial annulations, 

 and the ventral nerve cord does not extend in front of the 1st setigerous somite. 



The real distinction between the dorsal tactile filaments of the anterior 

 end and the lateral branchial filaments is, that the former are provided with 

 a groove similar to that which occurs in the occipital tentacles of Nerine, &c. 



Claparede's account of these filamentous appendages, which are so charac- 

 teristic of this genus, and which give it its name, is not quite correct. There 

 are two kinds of these filaments, — the tentacular, which are confined to the 1st 

 setigerous somite in this species, to the 4th and 5th setigerous in the following, 

 and' the branchial, which are present on the sides of a great number of the 

 somites. There is never more than one pair of branchial filaments to a somite 

 in the present species ; the attachment of the branchia is same distance dorsal 

 of the notopodial bristles. The branchia is a thin flexible cylinder, composed 

 of epidermis, muscular wall, and cavity. In the cavity run two longitudinal 

 vessels continuous with each other at the distal extremity of the filament; 

 a closely set series of transverse small capillary vessels connect these two main 

 vessels ; these run in the muscular layer close beneath the epidermis (see fig. 

 9 c). The tentacular filaments appear in the living animal opaque white, 

 while the branchia? are of a brilliant red : in spirit specimens the tentacular 

 filaments are still white, while the branchial are dark, sometimes quite black, 

 owing to the pigment, which is abundant in the epidermis of the latter. The 

 tentacle also consists of epidermis, muscular layer, and cavity. In the cavity 

 runs a single longitudinal pseudhajmal vessel, which ends caecally at the distal 

 extremity of the filament, and gives off no branches. On the ventral surface of 

 the filament is a single deep groove running the whole length of the filament, 

 and lined with a coating of extremely short cilia. When sections of the 

 tentacle are made it is seen that the formation of the groove is entirely due to 

 two parallel thickenings of the epidermis; no other structure in the tentacle 

 takes any share in its formation. The number of the tentacles is considerable. 

 In a large specimen we counted 10 pairs, and there is always attached to the 

 tentacle-bearing somite a single pair of branchiae in addition. These branchia) 

 are ventral in origin to the transverse series of tentacles. The number of 

 the tentacles, however, is not constant, but increases with the age and size of 

 the individual; in specimens 4 cm. long only 5 pairs are present. Claperede 

 attributes two grooves to the branchia;, and none to the tentacles, but his 

 account of the vascular supply is correct. He does not discuss the relations of 

 the groove to the epidermis. 



