254 MR. R. COLLETT ON BALZ NOPTERA BOREALIS. — [Feb. 2, 
individuals 320, in others as many as 340. No. 2 for instance had 
on its right side only 318, on its left 328.. The number appears to 
be rarely the same in the two jaws of the same individual. 
The front .plates were smal!, almost rudimentary, and formed 
double rows; these were difficult to count. The greatest length was 
attained at the commencement of the latter third of the series, where 
as a rule they measured 550 to 600 millim.’ 
From these measurements it appears that the length and number 
of the plates are not constantly greater in the right than in the left 
jaw, also that there is no constant difference between the plates in 
the two sexes. 
The hair-like bristles in which each plate terminates, and which 
form the most effective part of the straining-apparatus, are in this 
species unusually fine, somewhat resembling silky wool, and white 
* I give here the measurements of the baleen-plates of 4 examples, viz. those, 
of specimens Nos. 1, 3, and 5, and those of a fourth individual, the jaw of which 
lay on the beach. They are reckoned fr om behind forwards, so that No. 50 lies 
near the angle of the mouth, No. 250 nearest the symphysis of the jaw. They are 
measured from their base (in the freshly killed specimen) to the outermost 
point where the plates terminate and the bristles commence. 
No. 1. Female. Left all black; on the right side, the first 
slightly lighter colour. 
Left side 328 plates. Right side 324 plates. 
millim. millim. 
Hensthof no: D0. sc2cc.ss<e- 460 ING. CBO) ae: Hides. SERPs 430 
Pe NOS LOO wre 590 PT LOO ccaceuscchatvoess ates 560 
55 TOs Us o coe gees 520 | Pare 5) 0 op peomes Meee ieee eT 510 
* M10. 200 sess ADOSER - BID 035.0. c ona cues Pee 420 
= 10 Sige. A 240 ae RAD OF ene te ee eee 240 
No. 3. Female. All black. 
_ Left side 534 plates. Right side 328 plates. 
millim millim 
Length of no. 50 ............ 430 NOB OE rs cons cetnscns se sens tei 450 
A HMOs LOU eee cee NE We LOOM lescensct aide noeeeesee 540 
* noMlBOPAaeAN. 490 a ES OME iris tek ee 470 
© TIO ZOO 962325. 0tetlk 380 | ght (BOO se Seals HAGE 370 
. B10 S200 og Saterer ext 180 | Af 250 fs cc ce adatas tans pee reeee 210 
No. 5. Male. All black. 
Left side 318 plates. Right side 321 plates. 
millim. | - millim 
Length of no. 50 ............ 490 |. INO.g100 “steko ee ee 480 
+ mp: MOOS erect 640 94g LOO a, cee c thee hereeaeee 630 
OE, Seay ee Bae at BAe age eae 590 
- NO: 200K cee -gssaas 420 ! Si UD aztec tenceter sp sacee 440 
- TOs 200 raertntaten 250 5y DO a saeenus de cns ace Re 
Another example (sex unknown). All black. 
Left side 333 plates. Right side 539 plates. 
millim. | millim. 
Wo. 502 per geez ee DPT: igi gs ie aia se ae pa 500 
97 LOO! set ecees. sccaementee 570 SP ULOOA ~ HSikes wc Saedekeeeas 600 
hy LEO cere tees =a anee-ecenee 520 Be) a1 epee euer cee 560 
5 LUO stop tees teres ean ees 400 Fa | 9 ee eae eee een ay EEE E 450 
37. AOU guavevanawata este cote 250 5" | Pe aR Ree eee 240 
