24(1 



<>. Nordgaard. 



1901 and '-' 7 1901. From what I have been told by those enga- 

 ged in dredgim. 1- shells, I conclude that spawning also takes place 

 in the months of March and April. .Spawning time may therefore 

 be supposed to be from March to August. The spawning process 

 itself was seen quite plainly on s /s 1901- Both eggs and sperm 

 emerged through the anal sipho. The eggs were ejected in the 

 form of narrow, short ribbons which were, for the most part, bro- 

 ken up in the water and immediately sank to the bottom. A 

 siiiL'le female shell expelled so many that a large reddish-yellow 

 elevation was formed. Some of the eggs were whirled about in 

 the water and were greedily devoured by shrimps and barnacles; 

 some settled down in empty mussel shells and in the openings of 

 the lumps of Pomatoeerus triqueler, which covered the living and 

 dead specimens of M. modiolus. On closer investigation, it was 

 found that only a small number were fecundated. This was espe- 

 cially so with regard to the reddish-yellow mass above mentioned, 

 these eggs soon began to decompose. 



I also succeeded in seeing fecundated eggs at several stages 

 of development. The eggs, which were 0.078 — 0.09 mm. in diame- 

 ter, had no special colour. Division was, as in other mussels, com- 

 plete and inequal. There is reason to suppose that fecundation 

 took place outside the female's body. 



While spawning goes on, the eggs (and the sperm) are pressed 

 out through the genital openings, one on either side, then the 

 spawn passes through the innermost branchial passage, close up 

 to the hindermost constrictor and finally enters the cloacal room to 

 be expelled thence into the water through the anal sipho. The 

 reason for the eggs assuming the form of narrow, short ribbons 

 is probably that the genital opening is a column and not a pore. 

 The eggs rushed quite quickly out of the anal sipho, and it is 

 most probable that fecundation did not take place until they were 

 protruded here. 



On 12 A 1901. spawning of specimens which had been in the 

 aquarium about a year, was observed. Sperm was so plentiful as 

 to give the tank the appearance of being filled with milk and water. 

 There was at the same time a strong stream of water flowing into 

 the tank and this caused the eggs, for the most part, to whirl 

 about in the water. But as soon as the stream of inflowing water 

 was turned off, the eggs sank to the bottom. The process of di- 

 vision took place rapidly. Already in the evening of the same 

 day C'-'rl the eggs were divided into a large number of small balls, 

 and the next morning at 9 o'clock ( 13 /v) they had become larvae, 

 which were wheeling around by the help of cilia and describing tiny 

 circles. They had formed themselves into irregular small lumps, 

 which moved about at the bottom, their movements being quite re- 

 gular. Three days later {'''/-) the specimens were seen to have 

 larval shells and velum. These shells were 0.1 mm. long, their 

 ventral side being curved and the dorsal forming a straight line. 

 The velum could be drawn entirely inside the shells. At this stage, 

 the young Modiola possess a considerable power of motion, for they 

 swim quickly about by means of their velum. Instead of being 

 routined to a rotatory motion with very little change of centre, 

 they now moved more in a straight line. When they were six 

 days old, the specimens at the ,,velum" stage were seen to have 

 acquired circle shaped shells, the straight edge which represented 

 the dorsal side having become more curved. The length of the 

 shells was 0.156 mm., width 0.130 mm. The development of these 

 particular specimens was not followed further, but, from analogy 

 with other mussels, we know that the next important stage is the 



disappearance or alterations of the velum, while the foot now per- 

 forms the motion, until the little animal finally attaches itself to 

 some object or other. To catch these animals, a shell dredge of 

 a special construction is used, and also a „stikkert' - , which is a 

 kind of pinchers with three or four claws. 



Sometimes too they are taken by divers. They are taken out 

 of their shells after being brought to land. In addition to the 

 shells, the bundles of byssus and the gills are also removed. The 

 remainder is salted in kegs containing 28 liters. If the shells are 

 large, about 400 are enough to fill a keg, but as a rule from 700 — 

 800 are necessary. The price is about 9 kroner (10/ — ) per. keg 

 at first hand, and as the expense of catching them is very slight. 

 mussel fishing may be very profitable. 



I have referred somewhat at length to Modiola modiolus, as 

 this particular mussel plays an important part as bait in the cod 

 fisheries at Lofoten. 



Cyprina islandica, Lin. 



This animal is used as bait in ordinary fishing, but sometimes 

 too in fishing ocean cod. 



As for instance in 1896, about the middle of March, at Bal- 

 stad fishing station, where it was asserted that there were good 

 results when using this bait. 



Besides Cyprina, which was dredged somewhere in Napstrom- 

 men, Arenieola marina was also used, which was found near the 

 Balstad station. 



Zirplwn crispata, Lin. 

 This peculiar mussel was noticed by me in 1899, alive, in the 

 sand on the beach at the farm Sund, in Gildeskaal; several spe- 

 cimens were dug out and used as bait. 



Ommatostrephes todarus, Haf. 



..Sprut" and ..akker" are common names in the north of Nor- 

 way for this Cephalopod species, which, in the autumn come in to 

 the coast in large quantities and thence into the fiords, where they 

 are taken in thousands to be used as bait during the cod fishing 

 in Lofoten. In the Kvse Fiord in the north of Hinno a consider- 

 able catch of cuttle-fish has of late years been made. In many 

 instances, a single family has made an income of kr. 600 — 800 in 

 the course of a few weeks. 



Pandalus borealis, Kr0yer. 



During the investigations in the Skjerstad Fiord in April 1900, 

 several specimens of this species were met with, and 1903, Niels 

 Haagensen, who was my assistant at the earlier date, made some 

 trial catches with a shrimp trawl, and he succeeded in taking from 

 10 — 30 liters each time. So that it was thus proved that P. bore- 

 alis occurs in large quantities in this fiord. 



This species is now sent to Bergen and Kristiania to be used 

 as food in no small quantities, but in the north of Norway it is 

 more difficult to sell them, so that there is not much prospect of 

 making much profit on them. 



Haagensen, has. nevertheless, suggested that a trial should 

 be made to salt them, prepared as bait, for the fisheries in the 

 north. His suggestion might, at any rate, be found useful for 

 such times as there is a scanty supply of other bait. 



H. Kims, at Tromso in 1903 made investigations* with respect 

 to the occurrence of P. borealis in the Bals Fiord, the Tromso-sund, 

 the Kvalsund and the Kal Fiord. 



