ANNELID GENUS CAMBARINCOLA — HOFFMAN 281 



deavored to evaluate the systematic value of the previously used 

 characters. Goodnight, however, added little to our knowledge of 

 this general subject, and his references to the structure of the sexual 

 organs are meager. Finally, on the basis of his own knowledge of 

 branchiobdellid anatomy, Holt (1953) published a review of previous 

 work, and introduced information compelling greater attention to the 

 reproductive systems. 



The following discussion of anatomical characters which appear to 

 be of taxonomic significance summarizes the points of interest which 

 have been considered during the study of Cambarincola and related 

 genera. It has been found necessary to review each character regard- 

 ing its development in the family at large, and then particularly as it 

 occurs within the more circumscribed limits of Cambarincola. 



I. Body Form 



Branchiobdellids vary greatly in form, but the typical appearance 

 is that of an elongate fusiform cylinder, with a distinctly set-off head 

 and a caudal sucker, both of variable dimensions but normally smaller 

 than the head. In general each body segment is composed of two 

 subsegments, of which the posterior is usually a little larger in diam- 

 eter than the other. Several variations from this form occur: in 

 Xironogiton, Xironodrilus, and some related genera not yet formally 

 segregated from the latter, the body is strongly compressed dorso- 

 ventrally, broadest near the caudal end. In Xironogiton the body 

 outline is unusual in being very abruptly narrowed anteriorly, having 

 something of the shape of a tennis racket. In the poorly known 

 genus Triannulafa, each body segment is said to have three subseg- 

 ments instead of two, although an approach to that condition occurs 

 in the large species Cambarincola macrocephala. A terete body such 

 as described in the first sentence characterizes most species of bran- 

 chiobdellids, including all Cambarincola, and is probably the primitive 

 condition in the family. Flattened bodies are doubtless speciahza- 

 tions, although genera so formed are not always specialized in other 

 particulars. 



II. Body Size 



Owing to the normally extensive degree of contractability char- 

 acteristic of most oligochaetes, the subject of body size and propor- 

 tions is not an easy one to treat satisfactorily. Branchiobdellids in 

 hfe are able to double or halve their normal length during motion, 

 and preserved and contracted specimens give an inadequate idea of 

 the living animal. Yet with proper preservation, contraction is not 

 excessive and species can be compared in general terms of relative 

 size. Kjiown species in the family range from about 1 mm. up to 

 18 mm. or more in length. Intraspecific variation tends to increase 



