CIRRATITLIDJE. 239 



the circular muscular coat being well developed all round. The nerve-trunks are flattened 

 and lie in the hypoderm outside the circular coat. Both dorsal and ventral longitudinal 

 muscles have narrow fasciculi. The large size of the dorsal blood-vessel and its deep red 

 hue are conspicuous. A strong mesentery on each side is fixed to the ventral wall of the 

 gut, passes to the circular coat over the nerve-cords, and ensheathes the ventral blood-vessel. 

 The fibres of this mesentery are in various sections continuous, with similar fibres 

 ensheathing the dorsal trunk, and passing downward in close proximity to the gut. 



The branchial filaments in this group in some cases have two rows of cilia. In others 

 again the tentacular processes have a single row. 



De Blainville (1828) placed Girratulus under the Nereiscolecia, the fourth family of 

 the order Homocriciens, associating it with Lumbrinereis, Girrinereis, and Nainereis — forms 

 by no means closely allied. 



Audouin and Milne Edwards (1834) arranged the Cirratulids under their " Ariciens," 

 pointing out that Lamarck established the genus after the descriptions and figure of Strcem 

 and Otho Fabricius, these authors considering their form allied to the Lumbricidae. 

 Lamarck, however, thought otherwise, and Savigny showed how it differed from that 

 group, an opinion confirmed by Dr. Johnston, who, with Savigny and De Blainville, adopted 

 Lamarck's title. Audouin and Edwards discriminated between the branchiae and the cirri, 

 but they observed no eyes. Milne Edwards (1834) divided the group into two divisions, 

 viz. (a) species in which the branchial filaments were fixed to the dorsum of a segment in 

 the anterior region of the body, e. g. Cirrhatulus LamarcMi, and (b) species devoid of filiform 

 branchiae fixed to the dorsum e. g. Cirrhatulus Bellavistx, Blainville. Grube (1851) 

 adopted this arrangement, the genus being placed between Sphoerodorum and Aricia. 



(Ersted placed the Cirratulidae under his Ghxtopoda terricolina, the third group of his 

 Maricolae, and under the family Ariceae, as a genus of the Ariceae lumbricinse. Besides the 

 form of the body and the conical head, he describes them as having no branchiae, or small 

 ones in segments two to seven ; in the third or eighth a transverse series of branchiae ; 

 in the succeeding segments a pair, and bifid feet (duae pinnae vel fasciculi setarum 

 capillarium) . 



De Quatrefages (1850) describes the nervous system of Girratulus fuscescens as 

 composed of two cephalic ganglia, two slender oesophageal connectives giving off the 

 visceral nerves, apparently without a ganglionic enlargement, and a double ventral chain 

 bound into a single band by what he calls a dura mater. 



In " Cirrhatulus Lamar clcii " Dr. T. Williams figures the segmental organ as a loop 

 with the ends nearly approximated and placed vertically in each segment. The ova 

 escape from the segmental organ into a dependent tissue which fills " the segment." 



De Quatrefages (1865) placed the Cirratulidae between the Neriniens (Spionidae) and 

 the Chloraemidae, and considered their organisation generally approached that of the 

 errant annelids, though in some respects they came near the sedentary forms. He found 

 three plans on which the branchiae were arranged, viz. first in most segments of the body 

 except the two or three anterior and the last ; in the second group these organs form 

 transverse rows on the dorsal surface of the anterior segments; whilst in the third they 

 are disposed in pairs in four or six of the anterior segments. He did not clearly 

 differentiate between the cirri and the branchiae, and he appears to have entertained the 



