314 



48 



two, and vice versa. At the end of the tail the rows are often incomplete, lacking 

 upper or lower members. On the "hump" 3 large, anchor-shaped, marginal scutes 

 are developed, reaching from the base of the second dorsal and the anal to the 

 nearest members of the ordinary rows, being joined to these or interposed between 

 them ; thus, on this part of the tail, transverse rows of 5 or 4 members are found, 

 and probably a certain amount of stiffness is acquired in this way. Sometimes 

 only the dorsal set is firmly connected with the neighbouring upper scute, while the 

 ventral set is interposed between the corresponding lower ones, sometimes the 

 reverse is the case, and in some specimens both sets are firmly connected, hi 

 one (female) specimen of S. paradoxus 4 anal marginal scutes occur instead of 3. 



Setting aside the marginal scutes of the "hump" the other scutes might as well 

 be described as longitudinally arranged in 3 lateral rows*, an upper, a median, com- 

 posed of fewer but larger members, and a lower. The number of scutes in the upper 

 and lower longitudinal rows generally differ slightly, the one having one or two more 

 than the other, and generally the number is not quite the same on both sides; the 

 latter is also the case with the median row (comp, the table below, where the numbers 

 are given). The shape of the scutes is more or less that of a star, with 4 or 3 branches. 

 All the dermal scutes are provided with keels, most prominent in S. paradoxus, here 

 producing a spiny aspect especially on the slender part of the body and on the tail. 



The total number of transverse rows behind the pectorals, which naturally is 

 the same as that of plates in the upper and lower longitudinal rows of body and tail, is 

 for S. cijanopterus 28—30, for S. paradoxus 29 — 33 (for details comp, the table below). 



Number of dermal scutes. 



S. cyanopterus 



A d 



B d 



C 9 



D Ç 



E 9 



S. paradoxus 



A d 



B 9 



Narrow part of trunk + tail 



Median 

 lateral row 



left side | right side 



13 

 13 

 12 

 13 

 15 



13 



•20 ' 



13 

 14 

 13 

 11 

 15 



13 

 21 



— to — lateral rows 

 lower 



left side right side 



26 

 26 

 26 

 24 

 25 

 24 

 26 

 25 

 24 

 24 



28 

 25 

 28 

 28 



26 

 26 

 26 

 25 

 25 

 24 

 25 

 25 

 25 

 24 



26 

 28 

 29 

 28 



Total number of 



transverse rows, 



including the 4 on 



"thorax" 



left side right side 



30 

 30 (28) 

 29 (28) 



29 



28 



32 (29) 

 32 



30 



30 (29) 



29 (28) 



29 



29 (28) 



30 (32) 

 33 (32) 



* GÜNTHER (16 b, p. 151) only counts 2 rows; probablj' a misprint or a lapsus calami, since pre- 

 viously (42, p. 137) he gave the number correctly as 3. 



