ATLANT. DEEP-SEA EXPED. 1910. VOL. III]. 



MURAENOID LARVAE. 



43 



This table shows that only L. Anguillae 

 vulgaris, L. Synaphobranchi pinnatl and L. 

 Congrl vulgaris occur evenly distributed in 

 waters of various salinities. We may suppose 

 that the single specimens of L. Congri mystacis 

 (35-6—7) and of L. similis (35-2—3) were really 

 caught in water of a higher salinity, while the 

 nets were being lowered or raised. Most of 

 the "Michael Sars" larvae were thus taken in 

 water having a salinity exceeding 36 °/oo, and 

 the same thing may probably be said of the 

 other species of muraenoid larvae found in 

 the North Atlantic, most of which were caught 

 south of the Azores, whereas the isohaline of 

 36 7oo and the isothern of 15° at a depth of 

 100 metres run across the ocean from Gibraltar 

 to the northward of the Azores and to the 

 southward of the Newfoundland banks, as shown 

 in fig. 37. According to the material in hand, 

 the position of this isotherm and isohaline 

 should coincide with the northern limit of 

 distribution of most of the species of muraenoid 

 larvae and an investigation of this tract of the 

 ocean would probably have produced interesting results. 



The "Michael Sars" occupied a series of oceanic 

 stations (Stats. 64 — 72), cutting across the Z-shaped 

 curvature formed by the isotherm of 15° and the isoha- 

 line of 36 °/ 00 to the south of the Newfoundland banks 

 (see fig. 37). For this series of stations I have drawn a 

 section in fig. 38, showing isotherm of 15° and salinities 

 above 36 °/oo and on which I have indicated where tow- 



r OUNDLAND 

 71 70 69 



SARGASSO SEA 

 64 



Fig. 38. Section from the Sargasso Sea to New-Foundland. Black 

 denotes a negative haul, ring denotes capture of one larvae. 



Fig. 37. Isotherm 15° and isohaline 36 °/oo 100 metres below surface. 

 Stations 61—71 marked off. 



net hauls were made, an open circle being used for each 

 muraenoid larva captured and black dots for negative 

 hauls. A glance at this figure shows that 1 1 out of the 

 13 larvae procured at these stations were taken in water 

 having a temperature exceeding 15° and a salinity exceed- 

 ding 36 °/ 00 - One of the two "exceptions" is a transforming 

 Gastrostomus Bairdii, whose presence in deeper water 

 with a lower temperature and salinity is comprehensible, 

 the other being L. simiiis, of which another spe- 

 cimen was taken at a depth of 100 metres at the 

 same station, so that it was probably caught while 

 the net was being lowered or raised. The 19 hauls 

 taken beneath the surface where the temperature was 

 below 15° and the salinity below 36 °/oo were all 

 negative but for the two "exceptions" just men- 

 tioned. 



It is of special interest to notice that all the 

 hauls at Stat. 66, situated as shown in fig. 37 in 

 the narrow tongue of cold water protruding south- 

 ward, were negative. 



Although not many larvae were caught at these 

 6 stations, the positive and negative hauls are 

 distributed so characteristically in relation to the 

 physical conditions as to corroborate the conclusions 

 arrived at in regard to the distribution of muraenoid 

 larvae. 



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