According to the literature, the genus Spadella Langerhans includes several species, Sp. cephaloptera (Busch) 1851, Sp. schizoptera Conant 1895, Sp. moretonensis Johnston & Taylor 1919, Sp. sheardi Mawson 1944, Sp. johnstoni Mawson 1944, Sp. angulata Tokioka 1951, Sp. nana Owre 1963, Sp. pulchella Owre 1963. This genus apparently includes species having world wide distributions, and species with distribution restricted to small regions. At times, several species have been reported from the same geographical region. For instance, MAWSON (1944) observed Sp. cephaloptera, Sp. sheardi, and Sp. johnstoni off the coasts of New South Wales (from off Post Heaking to off Ulladulla). OWRE (1963) observed Sp. schizoptera and Sp. nana at Soldier Key (Florida), and Sp. pulchella in Magueyes Canal, La Parguera (Puerto Rico). YOSII & TOKIOKA (1939) reported Sp. cephaloptera and Sp. schizoptera from Misaki (Japan); see Table 2. Specimens of this genus have been obtained from near to surface location to a maximum depth of 100 m (MAWSON, 1944). Four specimens of Spadella were observed in the collections obtained by Dr. P. WAGENAAR HUMMELINCK in the Southwestern part of Bahía Fosforescente, east of La Parguera (Puerto Rico) at 1 meter depth on sandy bottom of Thalassia flat with Halimeda (Sta. 1423A), on the 17th September, 1963. This locality is close to the place where Sp. pulchella occurred (OWRE, 1963). However, the four specimens of Spadella from the present collections showed diagnostic characteristics different from those of Sp. pulchella and the other species of Spadella previously described. In order to compare the specimens here studied with the species that is most closely related morphologically, I requested the paratypes of Spadella pulchella Owre from the U.S. National Museum. In Table 1 are included the differential characteristics for the various species of Spadella, and Figure 36 presents illustrations of S. pulchella for comparison with those of the proposed new species.