399 Part TIL — Eighteenth Annual Repwt 



from the end of the furca and one from a notch on the outer margin ; 

 the small hair is also marginal. 



The male and female have each three abdominal segments. Those of 

 the male are nearly of equal size, but in the female the genital segment 

 is about as long as the combined length of the next two, and it is 

 provided on the ventral aspect with two moderately long setse. In the 

 specimen figured (fig. 15) several minute ova were observed attached to 

 these genital setre, as shown in the drawing. The fifth thoracic feet in 

 the female (fig. 18) are sub-cylindrical, and rather longer than broad, 

 and carry two apical setse. 



Monstrilla danai appears to be more frequent in Upper Loch Fyne 

 than in the seaward part of the Clyde. In a tow-net gathering collected 

 on the 28th November last (1899) near the head of the loch as many as 

 twenty-seven specimens of Monstrilla were obtained, apparently all 

 belonging to this species. But a much larger number of specimens was 

 obtained in a gathering collected, also near the head of the loch, in the 

 month of September immediately preceding. This gathering, which was 

 collected with the surface tow-net on the 29th of the month referred to, 

 was a small gathering, and contained a considerable quantity of fibrous 

 matter. It was not examined until the following month of March, when 

 over eighty specimens were obtained! The specimens comprised both 

 males and females, but whether they all belong to the one species I am 

 not yet in a position to say. The fact that such a large number of 

 specimens was found in a single small gathering is of no little interest in 

 its bearing on the distribution of these curious animals. 



Pseudanthessius thorellii (Brady and Robertson). 



1875. Lichomolgus thorellii, B. and R., Brit. Assoc. Report, 

 p. 197. 



This species, which is one of the Lichomolgidse distinguished by the 

 possession of elongated caudal lurca, has been obtained in dredged 

 material from various parts of the Clyde area. It is quite easily dis- 

 tinguished from Lichomolgus forficula, which also has long furca, not 

 only by the structure of the inner branches of the fourth pair of 

 swimming-feet and the difference in the proportional lengths of the 

 abdominal segments, but also by the difference in habitat. Lichomolgus 

 forjicula lives in the branchial cavity of large Ascidians, while 

 Pseudanthessius thorellii appears to live free amongst weed or zoophytes, 

 and perhaps also amongst Filograna. I have not on any occasion found 

 it naturally inside an Ascidian, and neither does Professor Brady in his 

 description of the species refer to it as a commensal. 



Hermanella arenicola (G. S. Brady). 



1872. Boeckia arenicola, G. S. Brady, Nat. Hist. Trans., 

 Northumberland and Durham, vol. iv., p. 430. 

 A specimen of this fine species was obtained in a gathering of entomo- 

 straca from Loch Gilp (near Ardrishaig, Loch Fyne), which is a new 

 Clyde Station for this species. The vicinity of Otter Spit is the only 

 other locality within the Clyde area that I know of where Hermanella 

 arenicola has been obtained. 



Asterocheres (?) echinicola (Norman). (PI. XIV., figs. 33-36.) 



An Asterocheres is obtained in the water passages of a sponge (Suberites 

 sp.), common both in the Clyde and Loch Fyne, which is closely allied to 

 Asterocheres echinicola (Norman), and which may probably be only a 



