122 AMPinURA SQUAMATA. 



Descrijyfion of a Specimen. — Dicameter of disk, 4.5"™- ; from outer 

 side of inoutli-shield to outer corner of opposite mouth-slit, l.Y"""" ; 

 width of arm without spines, .G"""- ; length of arm, 19""" ; distance 

 from outer side of mouth-shield to inner points of mouth-papilla?, 

 to that between outer corners of mouth-slits, .8 : .7. Mouth-pap illa3 

 regular, stout ; three on each side ; outer one longer than inner ones, 

 and about twice as wide ; two inner ones of about equal size, nearly 

 square, with corners rounded ; the innermost one runs upward to the 

 teeth. Teeth five, flat, thin, squarish ; lowest one smallest and most 

 jDointed ; uppermost one a good deal the largest. Mouth-shields broad 

 heart-shaped, with a sharp ]Doint within ; rather small ; length to breadth, 

 .3 : .4. Side mouth-shields comparatively stout and large, meeting within. 

 Under arm-plates shield-shaped, having an angle within, the outer side 

 nearly straight, and lateral sides a little re-enteringly curved ; outer 

 corners rounded ; length to breadth (sixth plate), .3 : .3 ; even the 

 plates at the base of the arm are separated by the side arm-plates ; 

 first plate diamond-shaped, very small. Side arm-plates encroaching 

 more below than above. Upper arm-plates rounded ; outer side nearly 

 straight ; inner and lateral sides included in a common curve ; all are 

 slightly sej)arated by the encroachment of the side arm-plates, except 

 one or two at the base of the arm ; length to breadth (third plate), .4 : .5. 

 Disk-scales of pretty even size above and below, the latter considerably 

 smaller ; above, about 25 to a square m'}ii. Eadial shields joined for 

 their whole length ; shaped somewhat like a slender pear-seed, but with 

 the inside edge straight ; their two sharp ends are separated within by 

 a single small scale ; length to breadth, .9 : .3. Where the scales of the 

 under surface meet those of the upper, there is a distinct line, made by 

 the upturned edges of the lower scales. Arm-spines three, short, stout, 

 of equal length, a little rounded and flattened, even, tapering, blunt; 

 upper one broadest and stoutest ; second, third, and fourth joints, only 

 two spines, which are stouter and more rounded. Tentacle-scales two, 

 rather short and broad, with a strongly curved, free edge ; standing to 

 each other at an ano-le somewhat less than a rio-ht ano;:le. Color, in 

 alcohol : nearly white. 



Variations. — The disk may l)e to the arms as 3.6 : 10, or 4.7 : 1G.5. 

 The mouth-shields vary in breadth. There are sometimes four arm- 

 spines on one or two basal joints. A. squamata has been dredged in 

 from three to six fathoms, and is found creeping over shells and stones. 

 When alive, its color is dark grayish-brown, with radial shields lighter 

 (Ayres). It stands very near to A. tenera and A. pugetana, but the 

 former has the middle arm-spine thickened at its base, and the latter 

 has arms about twice as long ; A. Puntarenoi has a notch in the outer 

 side of the lower arm-plate, A. mlcrodiscics has differently shaped u^oper 

 arm-plates, and A. violacea has much smaller mouth-shields. 



