14 



KR. BONNEVIE 



[REP. OF THE "MICHAEL SARS" NORTH 



The same intermediate stage is represented also in the 

 position of the osphradium, which lies on the left side of 

 the animal, but still very near the dorsal middle line. 



Locality 



Depth 

 metres 



Date 

 1910 



Number of 

 individuals 



Size 



St. 



Lat.N. Long.W. 



mm. 



49 



29" 8' 25° 16' 



50 



June 6 



1 <? 



47 



Eupterotrachea coronata, ForsUal. 

 (PL V, fig. 53-59). 



Eyes (fig. 55, textfig. A, 5 a) long, cylindrical; length 

 of the eye more than double the diameter of the lens. 



Nucleus long and slender, length abouth six times 

 the greatest width. It rises above the dorsal level of the 

 body for about V3 of its length (fig. 54, textfig. A, 5 b). 



Cutis smooth, with a few cuticular spots round 

 the base of the swimming fin (fig. 56, c. sp.), with an 

 irregular group of spines (sp.) anterior to the eyes (fig. 

 53, 55), and with tubercles (t) on the tail only. Here 

 they form two pairs of longitudinal rows covering the 

 lateral muscle bands, and also occur on the dorsal and 

 ventral ridges, and even on the tail fin (fig. 57). 



The osphradium (0) is situated on the left side of 

 the animal, and covered by a wall (without tubercles) 

 which forms a pocket4ike structure below the gills (fig. 54). 



Gills, ca. 15 in number, very unequal in size, a few 

 gills on the left side being large and well developed, while 

 the others on both sides are quite rudimentary (fig. 54). 



The muscle bands of the tail well developed, and, 

 as already mentioned, all covered by rows of tubercles. 

 The dorsal and ventral ridges end abruptly at the base 

 of the tail fin, so that the latter is leaf-like, and with a 

 deep incision, in which (in a few specimens) a tail filament 

 was found inserted (fig. 51). 



The radula (textfig. B, 5) contains 25 rows of teeth. 

 Median plate with 6 — 10 spines on each side of the long 

 and narrow middle spine. Intermediate plates with 

 a pointed secondary spine at the free ends. Lateral plates 

 very long, reaching the free end of the intermediate plates. 



Buccal teeth conical, 6 — 7 in each of two symme- 

 trical, longitudinal rows (fig. 59). 



Copulatory part of the penis 1 ) consists of a pair of 

 broad leaves, while the glandular part is a finger-like 

 structure tapering towards the distal end (fig. 58). 



J ) Reupsch (1912), in his very thorough essay on the anatomy 

 of Heteropods, maintains that the glandular, finger-like portion of the 

 copulatory organ plays the role of a penis, while the shorter ventral 

 protrusion is by him considered as a „Kopu1ationshilfsorgan" only. 

 His reasons for taking this wiew, differing from that of earlier invest- 

 igators, do not, however, seem clear enough for me to follow him. 



Size. This is the largest species in the material 

 from the "Michael Sars" Expedition, full-grown individuals 

 measuring up to 180—220 mm. in length. 



This species, which is well known from the Mediter- 

 ranean, was during the "Michael Sars" Expedition taken 

 outside this sea, as well as about the Azores and in the 

 Western Atlantic. 



Locality 



Depth 

 metres 



Date 

 1910 



Number of 

 individuals 



Size 



St. 



Lat. N. 



Long W. 



mm. 



19 



36° 5' 



4° 42' 



150—200 



May 2-3 



Ai 



150 

 ca. 180 



» 



— 



— 



450 



— 



1 d" 



ca. 220 



23 



35° 32' 



7° T 



200 



. 5-6 



A\ 



32 



47 



25 



35° 36' 



8° 16' 



1700 



. 7-8 



1 ¥ 



70 



29 



35° 10' 



7° 55' 



1000 



. 18-19 



1 ■? 



100 



51 



31° 20' 



35° 7' 



1000 



July 5-6 



1 f 



80 



52 



31° 24' 



34° 47' 







. 6-7 



{J 

 2 {s 



60 

 45 



53 



34° 59' 



33° r 



150 



„ 8-9 



Al 



27 

 28 



56 



36° 53' 



29° 47' 



50 



, 10-11 



1 d* 



80 



„ 



— 



— 



150 



— 



4 S 



20—60 



58 



37° 37' 



29° 25' 



150 



„ 12-13 



1 s 



100 



67 



40° 17' 



50° 39' 



100 



» 27 



1 <r 



130 



The vertical distribution of P. coronata, according to 

 the above list, seems to extend from the surface down to a 

 depth of 1000 and 1700 metres. It must, however be remem- 

 bered that a few specimens may have been caught during 

 the passage of the gear through the surface layers of the 

 sea, and therefore the records from stations 25, 29 and 

 51 should not be taken as real evidence of the occurence 

 of P. coronata in depths like those mentioned above. In 

 all probability it belongs to the surface-layers of the ocean 

 in depths between and 200 metres. 



As will be seen from the above descriptions of the 

 species of Eupterotrachea in the material from the "Michael 

 Sars" Expedition, they form a continuous series begin- 

 ning with E. hippocampus, through E. minuta, ending 

 with E. coronata. Within this series a development may 

 be traced from broad-based eyes and a broadly pear- 

 shaped nucleus on one hand, to cylindrical eyes and a 

 long and slender spindle-shaped nucleus on the other, 

 and at the same time from a median dorsal position of the 

 osphradium to a position at the left side of the body. 

 When more species of Pterotrachea have been accurately 

 described, this series may probably be augmented by 

 new points, either at the ends or in the middle of eth 

 series. 



