LABRADOR ASTEROIDEA — GRAINGER 



ar 



rAAAA/.- 



-H scobrior , 



C, crispotus 



'-'WW- 



7o«S 15 20 21 22 23 24 25 26 27 28 29 30 31 32 33 



Figure 2. — Temperature-salinity ranges of the Blue Dolphin sea star specimens. 



All the specimens show at least some characteristics of the form 

 tuherculata Danielssen and Koren, described as differing from 

 tumida in having relatively longer rays, in possessing dorsal 

 tubercles, and in having only single rather than double rows of 

 adambulacral spines. Arm radii are from 9 to 36 mm., R :r from 1.7 :1 

 to 2.7:1. Dorsal tubercles, present in all, vary greatly in their degree 

 of development, from only faint bulges to strongly developed pro- 

 tuberances spread conspicuously over the dorsal surface. There is 

 some evidence of correlation between size and tubercle development, 

 the largest sea stars frequently showing the most highly developed 

 tubercles. Adambulacral spines show a rather bewildering range of 

 variation, most being arranged in only a single row but many occurring 

 in 2 rows per plate. One-row series range from 3 to 5, having most 

 frequently 4 or 5 per plate. The majority of specimens show both 

 1-row and 2-row adambulacral plates, usually irregularly arranged, 

 the latter with up to 8 spines per plate. While there appears to be 

 some correlation between size and degree of development (above), 

 there is none apparent between either size and K,:r values or between 

 size and adambulacral spine arrangement; that is, large specimens 

 with well-developed dorsal tubercles (characteristic of form tuherculata) 

 may have low R:r values and frequent occurrence of 2 rows 

 of spines per adambulacral plate (characteristic of tumida). Little 

 work on variation within either form has been done to date. It ap- 

 pears from this collection that form tuherculata must be defined much 

 more widely than was done by Danielssen and Koren, and that its 

 differences from the stem form are far less distinct than they were 

 formerly thought to be. Possession of dorsal tubercles and presence 

 of only a single row of spines on the majority of adambulacral plates 



