DESCRIPTION OF AN ANTARCTIC SPECIMEN 13 



It may be concluded that the visceral organs of Gigantactis and Ceratias are, in general, similar, 



differing principally in the presence of two pyloric caeca in Ceratias. Kroyer's remarks on the viscera 



of Ceratias are confirmed. 



No internal or external parasites were observed in the Antarctic specimen. 



THE GROWTH OF CERATIAS HOLBOLLI 



Apart from the single discrepancy in the number of escal filaments, the foregoing description and 

 comparison establishes with fair certainty that the Antarctic specimen is, in fact, an adult of C. holbolli 

 Kroyer. 



Additional evidence is provided by an examination of the bodily proportions of this and other 

 specimens in the genera Ceratias and Mancalias. Parr (1932), identifying two Ceratiids as Mancalias 

 uranoscopus Murray, paid some attention to their proportions and attributed certain discrepancies to 

 disparity of age. Later Bertelsen (1943) compared the proportions of eight specimens of Ceratiids, 

 including species of Ceratias and Mancalias. Where there were disagreements in these measurements 

 (expressed as percentages of the standard length) he followed Parr in emphasizing that they could be 

 due to differences in size of the specimens. He concluded, therefore, that Mancalias and Ceratias could 

 not be distinguished by measurement, so that there was nothing here to contradict his demonstration 

 (based mainly on the mechanism of the cephalic tentacle) of the invalidity of the genus Mancalias. 



The discrepancies that Parr and Bertelsen noticed are immediately explicable if there is any allometry 

 of the proportions concerned. The investigation of allometry as a method in taxonomies has been 

 stressed by Huxley (1932) and subsequently discussed by Worthington (1940) and de Beer (1940). 



Accordingly, by substitution in the simple allometry formula* y = bx x , I have tested the measurements 

 of the eight specimens tabulated by Bertelsen, and five additional specimens which are of significance in 

 the systematics of the Ceratiidae. 



Table 1 shows the measurements of thirteen specimens of the genera Mancalias, Miopsarasf and 

 Ceratias. Besides the eight individuals previously tabulated by Bertelsen, the table includes Regan's 

 specimen, the new Antarctic specimen and the type of Mancalias sessilis Imai, together with representa- 

 tives of the two southern species ; viz. the type of M. tentaculatus Norman and the smaller of the two 

 existing specimens of M. bifilis Regan & Trewavas. I have been able to examine these last two specimens 

 in the Natural History Museum Collection. The measurements record the size of 21 dimensions or 

 parts in each specimen, but there are a few omissions. Dimensions are given as percentages of the 

 standard length, and from these the actual measurements have been recalculated £. 



The values for each dimension have been plotted against standard length on a double logarithmic 

 scale. The resulting graphs are shown in Fig. 5 («-«). It will be seen that except for graphs b and d, 

 the points for the graphs of each dimension give good agreement to a single straight line. In the last 

 two graphs (t and n), viz. those for diameter of eye and length of nostril, there are admittedly only four 

 points available, but the arrangement of these points strongly suggests a straight-line relationship, and 

 their inclusion is justified by inference from the conformity of the remaining seventeen graphs. The 

 appearances of graphs b and d are explicable and will be considered below. Apart from these, therefore, 

 it is seen that, in the specimens under examination, all the recorded dimensions have values showing the 

 straight-line relationship required by 



log v= log b + a log x. 



* For terminology see Huxley & Teissier (1936) and Reeve & Huxley (1945). 



f Regan & Trewavas (1932) included Miopsaras Gilbert 1903 with Mancalias. 



\ Except for nos. 1, 2, 9 and 12, where absolute measurements were directly available. 



