studios on marine Ostrarods 573 



uue ventrally,* at or somewhat tlistully of half the leiigtli of the joint; these two bristles are 

 sometimes very much reduced in the male, sometimes one at least may even be quite absent. 



Seventh 1 i m b: — This shows no dimorphism. — It varies so little in type that 

 it did not seem to be necessary to reproduce it for more than one species, Conchoecia symmetrica 

 G. W. MClleh. One of the two end bristles is rather long, the other is about half or not quite 

 lialf the length of the former. Both are of the same type: flattened proximally, narrowing 

 (listally to a fine point; very flexible, but with a strengthening list along one side, on the 

 proximal half of the bristle. This list is furnished with close, short, stiff hairs, arranged in 

 two rows; these hairs are so fine that they are almost impossible to establish with certainty. 

 These bristles are quite bare distally. The end joint is in most cases armed with fine hairs or 

 spines, which are often difficult to observe with certainty. Apart from these this limb is bare. 



Copulatory organ: — Unpaired. It issues on the left side** of the body just 

 in front of the furca, but is bent so that its point is situated in most cases in or even somewhat 

 to the right of the middle line of the body. It points obliquely forward and downward. It is 

 very powerful and large, more or less oblong and flattened at the sides. Near its posterior edge 

 runs the vas deferens, which emerges distaUy in a forward bending and in most cases strongly 

 chitinized point near the distal point of the copulatory organ or a short distance proximally 

 of it. A rod-shaped body penetrates into the vas deferens from the back. By means of special 

 muscles at the base of the copulatory organ this body can be pressed forwards and backwards 

 like the piston of a pump. In the middle part of the organ or in its distal half there is a rather 

 powerful musculature developed; most of these muscles run obliquely across the organ. 



Furca: — This has no dimorphism. — The lamellae are not sharply marked off from 

 the body proximally, nor is there any furcal field developed. The somewhat arched posterior 

 margin of the lamellae has a number of moderately strong or rather weak claws, in most cases 

 weakly bent or almost straight; the anterior ones are moderately long, the others decrease 

 rather uniformly and strongly in length the more posteriorly they are situated; there is no 

 division into main claws and secondary claws. The number of claws seems to vary very slightly: 

 seven or eight were observed on the species of this sub-family investigated by me. All the claws 

 are well marked off proximally. The most anterior claw (called by a special name ,,Hakenborste" 

 by C. Glaus) is situated a little way up on the anterior edge of the lamella and is in most cases 

 separated from the next anterior one by a somewhat greater distance than the distance between 

 the other claws. The armature of the claws in the species of this sub-family investigated by 

 me was as follows: The proximal part was often bare or only furnished posteriorly with a rather 

 small number of weak spines; sometimes, however, like the distal part, it is closely and finely 

 pectinated; this character is most frequently a variable one. Distally of this part each claw is 

 armed posteriorly with tw'o rows of close, conical, smooth, pointed spines, which are directed 

 obliquely disto-posteriorly. These rows, one of which runs somewhat laterally and the other 



* It is to be noted that G. \V. Muller, in fig. 13, pi. XXXII, 1906 a, lias drawn two liristles at this place 



for ..fiuco/icAoecfd CAiereAtae" and Th. Scott has done the same ill the case of E. (V Arcy-Thompsoni, 1909, pi. IV, fig. 10. 



** G. W. ^^^jLLER slates, both in 189'i and 1912, that the penis is situated on the right .side of the l)ody. 



ill the latter work this writer has also given a wrong position to the exits of the reeeplaiuhini seniinis and the ovidiut : 



he writes (1. c. p. .j:ij: ,,iler umfangreiche Penis liegt rechls, die Degatlungsoffnung links, die Mundung des Eileitersrechts." 



