98 



TBREBELLID^ 



Capillary bristles 



only in the 



anterior part of 



the body. 



Branchiae 

 ramose. 



Thr 



ee pairs. 



Two pairs 

 or one. 



Almost 



equally sub- 



fruticose. 



Arborescent ; 



post, smaller. 



Hooks 



Two pairs. 

 Capillary 

 bristles 



Amphitrite (0. F. M.). 

 Loimia, Mgrn. 



No eyes. Avicular uncini and 

 edge of bristles strio-serru- 



late 



Pectiniform .... 



/Produced into a 



Avicular. large lateral lip Lanice, Mgrn. 



Buccal J Short and narrow. 



segment Bristles with 



\ tips smooth . Terebella, L. 

 In fifteen segments. Bran- 

 chiae arborescent . . . Nicolea, Mgrn. 

 In seventeen segments. 

 Branchiae subclaviform . Pista, Mgrn. 



In sixteen segments 

 In fifteen segments 



Branchiae absent. 

 Capillary bristles. 



Fasicles of capillary bristles 



throughout the entire body. 



Branchiae 



One pair. 

 Capillary 

 bristles 

 In ten segments 

 In fifteen segments 

 In seventeen segments . 

 Ramose, arborescent, generally three pairs . 



/ Two, forming a contiguous 



series on each side . 

 Three. Fascicles of ( , , 

 bristles beginning j 

 on segment 



Filiform in 

 segments. 



transverse 



one branchiferous 



Scione, Mgrn. 

 Axionice, Mgrn. 



Leoena, Mgrn. 

 Lanassa, Mgrn. 

 Laphania, Mgrn. 

 Lepraea, Mgrn. 



Thelepus (Leuck.). 



Neottis, Mgrn. 

 Grymaea, Mgrn. 



After an interesting historical summary, De Quatrefages (1865), gives a brief account 

 of the structure of the Terebellidae, first investigated by Pallas, and subsequently by 

 Milne-Edwards, Grube and himself. He points out the delicacy of the cutaneous tissues, 

 the large size of the perivisceral cavity, the contents of which enter the tentacles (his 

 cirri). He mentions three pairs of " salivary glands " connected with the digestive system 

 anteriorly. The vascular system presents a dorsal and a ventral trunk, the latter 

 continued to the posterior end of the body, but the former at the junction of the oesophagus 

 with the intestine abuts on a large vascular ring surrounding the alimentary canal, and 

 giving origin to a slender dorsal branch, and a larger ventral trunk which extends 

 throughout the intestine. In the proboscidian region the superior branch furnishes trunks 

 to the branchia3. The blood is usually red, though Schmarda found it green in two from 

 Jamaica and one from Chili. The branchiae are the respiratory organs except in the 

 abranchiate types, where the cutaneous tissues subserve this function. The nervous 

 system shows a bilobed cephalic region. Anteriorly the ganglia are fused in the middle 

 line, but thereafter the chain is simple. The cords are separate in the posterior region. 



In his classification of the family into Branchiate, Abranchiate and Heteroterebellids, 

 he starts with the primary distinction of a body divided into two regions or composed of 

 one only, eight genera falling under the former, three under the latter, which he 

 distinguishes as the Heteroterebellids. The first series (Branchiate) is divided according 

 as they have or have not dorsal branchiae, those having three pairs of arborescent dorsal 

 branchiae belonging to the genus Terebella, with two pairs to Physalia, and with one pair 

 to Idalia. Of the others Terebellides has pectinate median branchiae ; whereas simple 

 cirriform buccal branchiae characterised Phenacia, and pinnate buccal branchiae the 

 Sabellidce. On the other hand cirriform and pinnate branchiae are both present in Isolda. 

 The last of this series is Apneumea with no dorsal branchiae, and which therefore forms 

 the second tribe ( Abranchiata) . The third tribe, as mentioned, has the body composed of 

 a single region, and two of the genera have arborescent dorsal branchiae, viz., Hetero- 

 terebella with three pairs, and Het&rophysdia with two pairs. Heterophenacia, again, has 



