POLYCH^TA SEDENTARIA OF THE FIRTH OF FORTH. 681 



except the tubes referred to. Eisig found these tubes full of spermatozoa in 

 both sexes, and believes that in the $ they act as penis, in the female as 

 vulva plus receptaculum seminis. 



As can easily be seen in a specimen of 8 mm. length, mounted whole in 

 Canada balsam, the ganglion of the 9th setigerous somite is continuous 

 ventrally with the epidermis ; dorsally it receives the anterior nerve cord, and 

 in front of this point both cord and ganglia are internal to the longitudinal 

 layer of muscles ; posteriorly both cord and ganglia are external to the circular 

 layer of muscles, and in contact with the epidermis. 



There are no pseudhsemal Vessels ; the body-cavity is crowded with red 

 nucleated corpuscles, which are present in great numbers (PL XLVII. fig. 43). 



Notomastus latericius (Sars). 



Notomastus latericius, Sars, Fauna littoralis Norvegise, pi. ii., 1856. 

 Capitella rubicunda, Keferstein, Z. f. w. Z., Bd. xii. ; Claparede, Beob. iiber. 



Anat. etc. an den Kiiste von Normandie, Leipzig, 1863. 

 Notomastus latericius, Malmgren, Ann. Polychseta ; Of. Kongl. Vet. Akad. 



Forhandlingar, 1867. 



The genus Notomastus was established by M. Saks, with the follow- 

 ing diagnosis : — Anterior part of the body composed of 12 somites, each 

 divided by a transverse constriction into 2 rings : 1st somite without, the 

 the other 11 with, on each side, two fascicles of capillary setse; no para- 

 podial processes. Posterior part of the body longer and thinner ; on each side 

 two slight parapodial tubercles transversely elongated, and bearing uncini in a 

 transverse series. 



It is extremely characteristic of this genus, that, as described by Sars in 

 his account of the animal, in the first 8 to 13 segments of the posterior or 

 uncinate region, the two notopoclial ridges coalesce into a single prominence 

 in the dorsal median line. 



Grube placed his genus Dasybranchus in the family Telethusidse, with 

 Arenicola. Sars thought Notomastus also belonged to the same family. 

 But Notomastus latericius has no pseudhsemal vessels, and has numerous red 

 corpuscles in the ccelomic fluid, in which respects its affinity to Capitella is 

 clearly shown. There can be little doubt that the Capitella rubicunda of 

 Keferstein and Claparede is identical with the N. latericius of Sars, and 

 the discovery of the corpusculated coelomic fluid in Notomastus belongs there- 

 fore to Claparede. 



We refrain from giving a specific diagnosis, because the species of the 

 genera have not been sufficiently compared. The colour is red. 



Habitat. — Several specimens were dredged in November 1886, in 6 to 12 



