318 MR. R. COLLETT ON CERTAIN GOBIOID FISHES. [Mar. 5, 



portion of the nose-leaf, and having also the last caudal vertebra 

 free. 



Ph. coronata, Peters, from the Philippine Islands, approaches this 

 species in size and in the remarkable length of the calcaneum ; but the 

 very different form of the nose-leaf and ears at once distinguishes it. 



7. On Latrunculus and Crystallogobius, two remarkable 

 Forms of Gobioid Fishes. By Robert Collett, of 

 Christiania, C.M.Z.S. 



[Received February 18, 1878.] 



Upon different occasions, at meetings of the Scientific Society of 

 Christiania, I have communicated my observations on a singular 

 group of our Gobioid fishes, which differ from the typical genus 

 Gobius not only in the almost perfect transparent body, but also in 

 differences in the structure of the scales, fins, and the form of the 

 body 1 . 



As the said group in several points offers much of interest, I will 

 endeavour to relate the general results of these researches, all of 

 which have been made in the Christiania fjord, a most favourable 

 locality for marine fishes and invertebrates. From these researches I 

 find :— 



1. Each of the genera, Latrunculus, Giinth., 1861, and Crystallo- 

 yobius, Gill, 1863, include one single species, L. pellucidus (Nardo) 

 1824, and C. nilssoni (Dub. & Kor.) 1844. 



2. Latrunculus pellucidus (Nardo) from the Mediterranean, L. 

 pellucidus (Kessler) from the Black Sea, L. albus (Parn.) from 

 Scotland, and L. stuwitzii (Diib. & Koren) from Norway are all 

 one and the same species. 



3. The males of both species have a dentition totally different from 

 that of the females ; in L. pellucidus these teeth are only developed 

 during the spawning-season. 



4. The female of C. nilssonii has the first dorsal and the ventral 

 fins rudimentary ; and the ovaries of this species reach back far 

 behind the vent. 



5. Both species are annual vertebrates, and accomplish their life 

 in the course of one year. 



Genus Latrunculus, Giinth. 



Genus Latrunculus, Giinth. Cat. Acanth. Fishes, Brit. Mus. 

 vol. hi. p. 80 (1861). 



Body transparent, elongate, rather compressed, covered with large, 

 deciduous, rounded scales attached to parallel muscular impressions. 

 Both sexes dentiferous, the mature male with a series of long teeth, 



1 Slsegten Latrunculus og dens nordiske Arter (Forli. Vid. Selsk. Christ. 1872). 

 Norges Fiske, rued Bemcerkunger om deres Udbredelse (Tillsegsh. tilForh. Vid. 

 Selsk. Christ. 1874). Om Shrgteme Latrunculus og Cryscaltogohius (Forh. Vid. 

 Selsk. Christ. 187(>). 



