350 STAITROCEPHALID^. 



and thus differed materially both from those described by Ehlers and from the living 

 types. The persistence of these annelids (if the interpretation put on these remains 

 is sound) is remarkable, as well as their adherence to a size akin to those of modern 

 representatives. In some the jaws more nearly resemble those of the genus Eunice 

 (Eunicites), in others they approach (Enone (CEnonites), in a third they are near Arabella 

 (ArabellUes), and in a fourth have the f acies of those of Lumbrieonereis (Lumbriconereites) . 

 It is noteworthy that in the Silurian beds the jaws have been found singly — a condition 

 possibly due, according to Dr. Hinde, to the abundance in the same beds of Ostracoda, 

 which may have preyed on the soft parts, and thus rendered them more readily 

 separated by the movement of the water. The locking together, however, of the parts 

 in certain forms would obviate such dispersion. Various irregular track-like markings 

 were observed by Dr. Hinde on the rock- surfaces where the jaws occurred, and may have 

 been due to the living annelids. Few instances of the occurrence of such fossils have 

 been recorded between the Silurian and the present period. As indicated elsewhere, 

 Ehlers is inclined to connect the foregoing structures with other phyla of the animal 

 kingdom such as the Rotifers. 



In this group are some of the giant Polychasts. Thus De Quatrefages found Eunice 

 Rousseaui from Banyuls 332 mm. in length and 16 mm. in breadth. On the other hand 

 Ophryotroclia puerilis, Claparede and Metschnikoff, is only a few millimetres in length, and 

 the male is unknown. This form has been found in the body-cavity of Gucumaria planci 

 at Naples, by Monticelli, 1 and Labroro stratus parasiticus by St. Joseph, in the body- 

 cavity of Eusyllis monilicorms, S. prolifera, Pionosyllis lamelligera, and Grubea clavata. 

 This shows a reduction of the maxillary apparatus, especially of the superior jaw. The 

 same author found others amongst algas (Rytiphlasa), so that parasitism may be temporary. 



Oligognathus Bouellide, again, was found by Spengel in the general cavity of 

 Bonellia, and in this form the inferior jaw is much reduced. 2 



Hsematocleptes terebellidis, Wiren 3 , occurs in the blood-lacuna in the wall of the 

 stomach of Terebellides Stroemii. The maxillary apparatus is also reduced. 



Euniceas appear essentially to be dwellers in cracks and crevices, some especially 

 haunting muddy fissures (e.g., Marphysa sanguinea.) The bristles of this species and its 

 great power enable it to adhere so firmly to its tube either by the anterior or posterior 

 end that rupture ensues before extraction. Small twigs on the stem and branches of the 

 Antipathidas are modified to form a tube for these annelids (Marphysa and others). 



STAUEOOEPHALIDiE. 



Eunicea prionognatha dicopa (Ehlers, 1868). 



In this group the dorsal longitudinal muscles are lappet-shaped in transverse section, 

 the broad ends being inferior. The ventral longitudinal muscles are massive with convex 

 borders inferiorly. The oblique muscles pass below the nerve-cords, which have a single 



1 ' Monitore Zoolog. Italiana/ Fierenze, 1892, No. 12, p. 250. 



2 f Mitth. Zool. Stat. Neap./ 3 e Bd., 1882, pp. 15—52, Taf. ii— iv. 



3 ' Bihang till K. Sv. Akad. Handl./ Bd. xi, No. 12, 2 pis., 1886. 



