12 Annals oj the South African Museum. 



In those specimens in which the gills are well expanded they are 

 seen to be of the pinnate type, as is clearly indicated in Kinberg's 

 figures IA, IP. The larger gills of the type specimen consist of 

 sixteen to twenty axes on each of which lateral branches are borne. 

 The longest axes of the middle gills are 7 mm. in length and bear 

 about sixteen branches on each side. The gills of the Saldanha 

 specimens are of exactly the same type. The ninth right gill of 

 one of them was examined in detail ; it consists of nineteen axes 

 connected by a short common basal piece less than 2 mm. in 

 length ; there is not a well-marked web -like membrane between 

 the bases of the gill axes of this species, such as is often present 

 in large Laminarian specimens of A. marina. The longest axis 

 of this gill is about 7 mm. in length, and bears on each side fifteen 

 branches ; the shortest axis is rather less than 3 mm. in length, and 

 has six pairs of lateral branches.'" The lateral branches, though 

 often opposite or paired, are not always so arranged ; on some axes 

 or on some portion of certain axes they are alternate. The sub- 

 sequent branching of the lateral twigs is either dichotomous, or, 

 especially in the larger ones, approximately pinnate. 



INTERNAL ORGANS. (Fig- 5.) 



The internal organs of the type specimen and of two of the 

 Saldanha examples have been examined. 



Septa and Muscles. 



The three septa, present in all known species of Arcnicola, are 

 found in A. loveni in the usual positions, namely, at the anterior end 

 of the first, third, and fourth chaetigerous segments. 



The strong first septum (S') bears two enormous, backwardly 

 directed pouches (S.P.), much larger than those of any other 

 species. In the three specimens examined these pouches are 25 

 to 26 mm. long ; they are about 3'5 mm. in diameter in front, but 

 taper gradually towards their blunt posterior ends. The wall of the 

 pouch consists of four layers ; externally and internally there is a 

 very thin film of coelomic epithelium, between which are two series 

 of muscles. The outer layer of muscles is about '5 mm. thick and 

 its fibres are chiefly circular in direction ; the inner one consists of 

 series of stout longitudinal bands, similar to those seen in sections 

 of the body wall, which project into the lumen of the pouch, and, 



* A gill axis, intermediate between these in length and number of branches, 

 is seen in Fig. 2. 



