RICHARDSON and JOSEPH: LARVAE AND YOUNG OF BOTHIDS 



Table 5. — Statistics describing the regressions of body measurements on standard length for juvenile and adult stages 

 of Enopiis inicrosioniu.s and Ciihciricliihys arctifrons. The independent variable X is standard length in all cases. 



X - Mean value of X 



Y - Mean value of Y 



N  Number of specimens examined 



b - Rote of increase of Y with respect to X 



a - y^intercept of regression line 



Sy  Standarcj deviation of the regression 



r - Correlation coefficient 



relation to SL in C. arctifroufi than in E. micro- 

 stomus larvae except depth at anus and depth 

 behind anus. Thus larval growth patterns sup- 

 port the fact that, as adults. E. mio-ostomus is 

 the deeper-bodied of the two, while C. arcti- 

 frons has larger eyes and a larger mouth. 



In larvae of both species, the rate of increase 

 of depth at anus is greater than the rate of in- 

 crease of depth behind anus. Yet depth behind 

 anus/depth at anus approaches and eventually 

 exceeds 1 as the larvae undergo metamorpho- 

 sis and depth behind anus becomes the deepest 

 part of the body. Thus, the rate of increase of 

 depth behind anus should be greater than depth 

 at anus. 



For juveniles and adults, head length, eye 

 diameter, upper jaw length, and snout to anus 

 length increase at a faster rate in C. arctifrons 

 while all components of body depth (depth at 

 anus, depth behind anus, peduncle depth) in- 

 crease more rapidly in E. microstomus. Snout 

 length in both species increases at about the 

 same rate. 



The data indicate decreases in rates of growth 

 of head length, snout length, snout to anus 

 length, upper jaw length, peduncle depth from 

 larvae to adults of both species. Rate of growth 

 of eye diameter is nearly the same in larvae and 



adults of both species. Depth at anus decreases 

 and depth behind anus increases in growth rate 

 from larvae to adults of both species. 



Some degree of error exists in these calcula- 

 tions because of specimen shrinkage, wide area 

 of collection, and varying lengths of time of 

 preservation of specimens. Results presented 

 here may differ from those obtained from 

 newly preserved material. 



Comparative Developmental Osteology 



The discussion presented here is based en- 

 tirely on stained material of approximately 

 100 larvae and of 10 juveniles and adults of 

 each species. No dissections were made. The 

 smallest stained larvae examined were 4 mm SL. 



Sequences of ossification are consistent with- 

 in each species, but the size at which specific 

 bones begin to ossify may vary from specimen 

 to specimen. The sizes given here indicate 

 general trends of the larval specimens exam- 

 ined from VIMS 1962 collections. 



This study is not intended to be a descrip- 

 tive osteology of each species but rather a com- 

 parison of development of the two. Discussion 

 of skull bones is mainly limited to those of the 

 branchiocranium which are identifiable in early 



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